The fact people have a hard time understanding this is fascinating. Hot gasses take up more volume. When those hot gases, cool down, there is less volume. Thus in his first experiment when the hot gas is cool down when the lid goes on, there is less volume and the atmosphere pushes the water into the container. It really that simple. there are much more complicated things in physics… I love your videos, very good job❤
No. What you say doesn't really make sense either. Gases fill the volume of a container so they don't take up a constant volume. However, for the same moles of gas, the pressure the exert will be inversely proportional to the volume they currently occupy. So expanding a gas without adding more molecules will drop the pressure. But increasing the temperature increases the pressure, so in this case it will cause an expansion as it can push against the water surface more than the atmosphere. This pressure drops when it cools back down and goes back to the original volume.
@@kbee225 your explanation is more technical, thusly, It is a better explanation than mine. However, the gases in the container do take up a specific volume once you compress them to a certain point. Absent the compression they only cause a pressure differential depending on the conditions in said container. The burning candle replaces the oxygen it reacts with, with carbon dioxide and various other compounds from combustion, so in the end, the pressure is directly related to the temperature and thusly the volume of said gasses right? I did not major in physics, but I think me and you are saying the same thing, are we not?
@@jacksondodd8835I think the issue is that you're trying to say - "Matter in = matter out and Temperature follows the constants." in 500 words so you sound like a PhD when this is actually an entry level observation. If anyone didn't understand - the video explains it. If you want to teach, explain something the video doesn't.
@@KrakenIsland64 so if you were going to explain to a child, the phenomenon going on in his video, you would say what you said? Matter in matter out, temperature follows Constance? Do you think a kid would be able to understand that? if you said that to a child and didn’t show them the video, could they re-create the experiment? but yet this is a phenomenon that a kid could understand it is not complicated physics but congratulations, your explanation made it complicated It needs lots of context to understand in the specifics of this experiment . My explanation might be long in words, but it is easy for somebody to visualize . You would need to know quite a bit of physics to understand your explanation. -- Edit : I reread your response and I see what you are saying by adding something new but I was not trying to add anything new. I was trying to explain to people on here who had commented who couldn’t understand the basic level much less your explanation, my friend.
Maybe it could be instructive to burn steel wool under the glass. It binds the oxygen as rust isntead of releasing it as CO2. Should you get a different effect, especially after cooling down?
That would be a nice counter-point to his last statement. No, indeed you can't create or detroy matter with a candle but you can change the state of matter and this would affect the pressure.
Thanks! Always wanted to see that experiment done. You can't create or destroy matter with a candle, but you can increase the number of molecules in the gas, increasing the volume consequently. The fuel of the candle is a hydrocarbon, made up mainly of hydrogen and carbon. Each molecule of O2 in the initial gas will produce either one molecule of CO2 (without changing the volume - number of moles) or two molecules of H2O, increasing the number of moles in the gas (and volume, consequently). The water level seems to return to its initial position only because of the condensation of a significant part of the water vapor when it comes into contact with the water and the glass wall. The thickness of the water level mark in the glass helps to hide any discrepancy between initial and final volumes.
Gas pressure is not dependent on the TYPE of gas you have. It only depends on the TOTAL AMOUNT of gas molecules you have. So if you use up six O2 molecules to burn the candle, resulting in three new CO2 and three new H2O molecules... you still have a balanced number of SIX total gas molecules produced as you use up the original SIX gas molecules. So the gas pressure before = the gas pressure after. And it's the gas pressure that balances the water level. Thermal expansion, heating the air in the jar from the flame, has a bigger impact on the water level than the chemical reaction of the oxygen with the candle. Hot air is higher pressure so the water level drops. Cooler air is lower pressure so the water level rises as the candle extinguishes and the air in the jar cools down.
C25H52 + 38 O2 = 25 CO2 + 26 H2O C25H52 + 25.5 O2 = 25 CO + 26 H2O in both scenarios, we started with 38 or 25.5 gas molecules, ended up with 25 gas molecules. Not to mention CO2 would be absorbed into water at a muncher higher rate.
Almost correct. 1) it’s not the amount of gas that matters, but the number of molecules. 2) this is an approximation for perfect gases that assumes a gas molecule occupies no volume and that disregards any attractive / repulsive forces between gas molecules.
Remember to make sure your reaction is balanced. 6O2 cannot turn into 3CO2 and 3H2O as that would require 4.5O2 molecules. Other than that you are correct. As well it is good to remember that the water molecules can condense which lowers the total number of molecules in gas phase
O2, becomes CO2, amount of molecules is the same and gas takes always same space IF it has same temperature. In this case candle makes gas a bit warmer, which causes it to expand, push a little water out and to create water vapor. When temperature will balance with outside, water level will go to original position.
nah. Candle is not C. Candle is close to C25H52. The H in candle will bond with O2 and form H2O which after cooling down is a liquid. C could burn completely and form CO2 and incompletely and form CO. However the is just too much H element. C25H52 + 38 O2 = 25 CO2 + 26 H2O C25H52 + 25.5 O2 = 25 CO + 26 H2O. In both reactions, you have less gas molecules after the reaction thus the amount of gas molecules reduces in the closed system.
@@honggao9610the C in CO2 and H in H2O were not in gas form, so you have roughly the same amount of gas volume. Some of the water will condense, but either way most of the air in the glass is nitrogen that doesn't react at all.
@@klh_io you don't seem to understand. According to the ideal gas question, it doesn't matter what the molecule is, all that matters is how many molecules there are (moles). So if I start with 38 molecules of gas (O2) like honggao mentioned above, and go to 25 molecules of gas (CO2) since the water will most likely fully condense (assuming the air space in a closed container with water should already have 100%RH) , then you see a drop in pressure, and that is directly due to combustion. @honggao9610 is correct.
It’s the laws of conservation of energy/mass. Energy/mass can neither be created nor destroyed, only changed. The oxygen is transformed into carbon dioxide and water vapor, equaling a net zero change in water level. Neither mass nor energy of that closed system are added or removed, only rearranged.
I would expect a drop in pressure if this is the case. Assuming the iron can keep reacting to deplete the oxygen levels to near zero. Then if there is enough iron to react, the pressure should drop by 20% as this is the partial pressure of O2 in our atmosphere.
In that case the amount of gas would reduce, because buring iron forms iron oxide, which is a solid instead of a gas. With the candle, carbon in the parrafin is combining with the oxygen to form carbon dioxide, another gas, and for each mole of O2, you get one mole of CO2, so you end up with the same total volume of gas in the end. Technically there is a little water vapor as well, but that quickly condenses onto a liquid on the glass.
@@RazzleberryHazeit gains mass because the end product is the steel wool mixed with the oxygen it pulled from the air. And unlike a candle where the products from combustion disperse in the air the products from steel wool remain solid. It's basically just rust.
The candle wax is mostly hydrocarbon when it burns completely there should be some volume change. 23N2(g) + 6O2(g) + 4(CH2)n(s)-> 23N2(g) + 4CO2(g)+ 4H2O(l) Or about 6%. Assuming the room is 20°C and the air is at 50% relative humidity then it can hold about another 1% of water vapour before it condenses into the droplets on the glass. The flame is yellow because soot is glowing yellow hot. Soot is only formed when there is incomplete combustion. Two molecules of carbon monoxide (CO) as it cools disproportionates into soot (C) and carbon dioxide (CO2), so there is probably some carbon monoxide in the gas.
@jeroennoordkamp3416 33 molecules (23+6+4) of gas initially reduced to 31 molecules (23+4+4) of gas. 1 ot 33.333... is 3% so 2 in 33 is a little over 6%
Doesn't condensation occur when relative humidity is at 100%? Relative humidity being at any given temperature the amount of water the air can hold.your claim that condensation would occur at 51% humidity just seems implausible.
Each O2 becomes CO2 or 2H2O. So overall gas increases. Bu H20 can liquefy. So once temp and humidity are returned to initial values, there should be slightly less total gas.
Yeah. Given that the fuel is paraffin, you get about 34% more gas than the gas (O2) used, but only 65% of the O2 used as CO2. I imagine that a fair amount of the water stayed gaseous because otherwise it'd appear that the volume should be 65% of what it was. Or maybe you get a lot of CO as well.
@domvasta Yes, that is a good point. The more I think the more factors I see I missed. There would also be some carbonised soot that only loses H but the C doesn't react. Also, CO2 will dissolve into the water with a higher frequency than O2. And the volume of the candle is reduced. I guess this is why physicists love frictionless spheres, not cows.
@@Tomyb15A candle won't burn atmosphere to 0% O2. There are (preventive) fire suppression systems for datacenters and libraries that reduce oxygen to 15% to prevent accidental fires. I assume a candle is more effective and will still burn at 15%, but certainly not down to 0%.
I just watched the initial video a few hours ago with my friend. We had come to the agreement that you were right basing our arguments on the principle of conservation of matter. Thank you for this follow-up. Solidified our arguments
Basic chemistry. You cannot create nor destroy anyone element. However you can convert elements from one to another combining and dividing creating new compounds with the addition and release of energy.
Nice experiment! The last sentence implies a misconception: You dont have to destroy or create matter to make the waterlevel rise above the initial hight. You would just need a reaction that chnages the volume (not the mass).
Also the net mol values of gas are the same, since we are not working in extreme conditions we can assume ideal gas behavior where pressure=(nRT)/V, all the values thus remain constant
Now, I have wondered how the candle is supposed to "take" the oxygen as paraffins react to water and carbon dioxide (in case od ideal combustion). Thanks alot for your video and explanation.
By the ideal gas law, PV =nRT or assuming the temperature and pressure are constant when equilibrium reestablishes after the jar cools back down, the volume will depend only on the ratio of number of moles of gas present before and after burning - since RT/P is constant. The effect of the temperature increase while the candle burns can likewise be calculated. No reference to the conservation of mass required, just a basic understanding of chemistry and physics. But a great demonstration which gets people reasoning, well done
The water level changes due to the expansion of hot gas, but after cooling, PROVIDED THE SYSTEM IS ACTUALLY CLOSED, you will not end up with any more or less gas. Literally conservation of matter, the water level changing has everything to do with heat and gas pressure from expansion, not from total amount of gas changing.
It's not create or destroy matters It's changing the Atmospheric pressure because of the content in the closed system like conversion of the air(O2) into something different The density also matters
Candle wax molecules consist of H and C atoms, with approx. twice the number of H atoms as C atoms. The O2 molecules are used to create both CO2 and H2O, spreading the available O atoms over both. The result is that the number of gas molecules created is about 33% more than the O2 molecules used. Air consists of approx. 20% oxygen. Therefore, if all oxygen was used, the air should expand in volume with about 7% Now, we can clearly see condensation on the glass, so part of the water condenses out. But are you sure that the expansion is only because of the heat?
Remember volume is not a comserved quantity. The mass of the system is constant but mass from the candle goes into the gas phase which changes the total volume. Since density is normally constant you would think volume is conserved but you cannot make that assumption when reaction or temperature change is involved as is shown in this system.
Combustion reaction is equimolar, same moles on each side, same amount of gas, same pressure (if ideal gas but it's pretty much ideal at 1 atm) so we would never expect the pressure of the gas to go down in fact we expect the gas to heat up from heat of reaction and equilibrate at a larger volume. I remember coming across this problem a while ago but I've never seen one where the entire volume of the gas is contained like this! Good experiment! You should do one with steel wool burning since in that reaction there is gas absorbed, it would be interesting to see whether the heating effect from the combustion or the removing of oxygen would win. When the temperature returns to normal the water level should actually go up. Bringing a monometer in could actually help explain it as well.
In this case it's not the same amount of gas, as also some water vapor is formed which condenses quickly to liquid.... Would be the same wit Steel wool. Remember there is only 20% of Oxygen in the air, and the fire will get extinct at about 15%. So the effect would still be low. However this effect is irrelevant in comparison to the expansion by heating.
@@thomasflototto9064 I understand the mechanics I'm just interested. I guess you can speculate the heating is more effective but what I want to do is calculate which one will win, which you are right it does but I want to see this guy do it with his kit.
@@thomasflototto9064 also the water level barely changes if at all so the condensing water has very little effect on the end result. With the steel wool the end result will have the water level rise as long as the system isn't adiabatic.
This is pressure working on the system. Too much pressure inside pushes water out. And when the candle is put out, the air cools thus reducing the pressure and water is sucked back in
Well, suction can be achieved a few ways, voiding the gas Inside or heating or cooling which is the case here. The air inside was heating until the fire went out then it cooled and sucked in.
Oxygen only accounts for 21% of the air volume at sea level... even burning all of the oxygen out still leaves almost 80% of the air. Now, consider that burning the candle releases gasses back into the container. Not really gaining or losing much at the end of it.
The H element in the candle will need to bind with O2 as well…. C25H52 + 38 O2 = 25 CO2 + 26 H2O. Gas molecules started as 38 + other, ended as 25 + other. So it reduced. Real reason water level didn’t not go up is. O2 is only 21% of air, and the candle stopped burning properly only consumed properly less than 10% of O2. 38 to 25 is a minor reduction, so probably less than 2-3% volume reduction which can’t be observed with your set up.
About that last thing you said, that you can't create or destroy matter with a candle. That is true, but you can turn one substance into another through a reaction, where the product has a different density at the same temperature and pressure. If the jar was pure oxygen and hydrogen and you somehow prevented the jar from blowing up in your face after lighting the candle, you would find a jar full of gases turn into a jar with water vapor. That water vapor will try to condensate and turn into a tiny amount of liquid water and a whole lot of vacuum that will suck the water from below. Sure, in this experiment it's just heat, cause the combined products (CO2 + H2O) ain't that much more dense in room temp than the ingredients (O2 + carbon-containing fuel in the candle), but the idea that it can't be the consumption of oxygen into another compound - not entirely nonsensical.
That's true. A very correct explanation. The amount of carbon dioxide and water vapour created is almost equal to the amount of oxygen used up. The partial vacuum created inside is due to two factors. 1. Initial Expansion of gas due to heat which pushes the gases out of the plate and then when flame goes out the gases contract and pull in some water. 2. Condensation of water vapour into water on the sides of the glass tumbler. These two phenomenon combine to create partial vacuum which ultimately pulls in water. If solely consumption of oxygen were the reason then irrespective of the number of candles you use the total rise of water would have remained steady at about one fifth the height of the glass tumbler. But if you increase the number of candles the rise of water will be more. Hence the explanation here is correct.
You can’t create or destroy matter (except when it turns into energy) but you can do a chemical reaction which changes the volume from beginning to end.
Chemical reactions actually cause a gain or loss of mass proportional to the energy produced or consumed. Energy is the constant that can’t be changed. Chemical bonds have tiny amounts of mass that are either destroyed to produce energy or created to store energy. Most chemical reactions do both but the sum of mass changes will be your energy released.
@@Playingwithproxies E=m*c^2 => m=E/c^2 . c^2=9*10^16 m^2/s^2. So the factor between Energy and mass is extremely large. And thus if the candle loses 100J of Energy to environment via heat, it will only loose 1.1*10^(-15)Kg of mass. Thats like nothing. Nobody can measure the mass of a candle down to this accuracy.
If it wasn't so explosive, an atmosphere of hydrogen and oxygen would prove that. First a rapid explosion, then almost a vacuum... because the gasses are way less dense than the water they turn into.
I missed that point. He was referring to the no such thing as a free lunch law of thermo. But yes as you say, that's referring to energy and not matter.
in the other experiments where the water level rises, it is because in those scenarios the air inside is heated enough that some of the air actually bubbles out the bottom. That part of the other experiment is carefully engineered out of this experiment.
Ok,but what you are ignoring, is that volume is not conserved in a chemical reaction, even if temperature is the same. In this case a simplified reaction equation is: C+O2 -> CO2. Now we got one O2 molecue plus one Carbon molecule at the beginning. In the End we have one molecule of CO2. The CO2 will have the same volume as the initial O2 after the reaction, as PV=NkT. But the Carbon is now part of it. The Carbon,which has used extra space before, now does not use extra space! So the volume still decreases approx. by the burned up volume of the candle. This would be true,if the candle was madw out of carbon..However it is made out of wax, so it produces also water and some other stuff. So if you consider this, then in the end the volume might even be bigger than before. I dont want to calculate this, but i just want to point out, that while mass is conserved, volume isnt.
The energy being used is within the container, it didn’t lose or gain it just explained as far as it could and then contracted back to even the pressure that was used
1. the candle does consume most of the oxygen. 2. it does create co2 and h2o but the water vapor shold turn liquid as their boiling point is way above room temperture. the lower than atmospheric pressure does help sustain more water vapor than in an open container but still.
you can actually see it creates more gass, as the water level goes from the top of the mark on the glass to it's buttom. creating and destroying matter got nothing to do whatsoever with that experiment. it is about creating or destroying volume by transfering matter from solid to gass state. you can create or destroy volume without creating or destroying matter. for example - any explosive creates tons of volume without creating or destroying matter.
CxHy(s)+ (x + y/2)O2(g) -> xCO2(g) + yH2O(g) Initially, you'd expect the gas to expand as it's both heated and transformed into (y/2) more molecules. Then it should contract as H20 condenses, CO2 dissolves into the water, and after the flame goes out, the gas cools. That assumes complete combustion, which the yellow flame indicates is not the predominant reaction. Solid carbon and gaseous carbon monoxide are also produced, stretching the O2 reactant further.
This is a pressure related phenomenon. The candle cant burn a large quantity of oxygen anyway before the concentration drops below a critical threshold. The volume difference assuming constant temperature should be small in comparison to the effect of the pressure increases impact.
Before you take any actions the water level in the jar was higher than the ordinary level of water in the tray! How did you get water to that higher level in the jar than the surrounding, in the tray? I appreciate the explanation, but I'm feeling like there might be something I'm missing or a trick involved. Could you please clarify that?
Could of been a couple tricks. Easiest probably being to lower the air pressure in the cup by removing some air, thus sucking the liquid up higher into the cup. A small hose could accomplish just that.
@@censorsstarveor he heated the air in the jar, so that when it cooled down, it contracted, allowing the outside air pressure to push the water level up
The only reason why the water level rises in some experiments is because they don't have the cup in the water while they light it they let the candle burn with a space underneath for gases to escape and when the air is heated in the cup and then you extinguish the candle then place it back in the water it will cool and suck water in. It's sad how dumb people are now
1 mol of gas takes up 22.4 Liters of space. No matter what gas it is at Atmospheric pressure. If The reaction that takes place converts 1 mol of o2 to 1 mol of Co2, no change in volume should take place other than that which increases the temperature and pressure. There is also vapor which undergoes a phase change
@guodlca you don't know what the chemical structure of the wick and wax are. You can't do the balanced reaction without knowing. That's why I generalized.
So in the usual experiment is that the expanding air actually leaked out of the glass from the bottom and can't get back in. When the air cools from the candle dying, the air volume goes down and the water take its place.
Precisely, from V amount of oxigen burning a paraffin oil or vax, you get 2/3V carbon dioxide and 2/3V water. It is more than the initial gas (in terms of number of molecules, and in terms of volume on the same temperature). If water condeses, it is less than the initial gas. You cannot destroy matter in this way, but in gases the number of molecules matters, not the weight or the number of atoms within the molecules .
You can't create or destroy matter, but the reactions can create new compounds with different densities to the original ones. Respiration is a prime example of that. Could that be where the confusion lies or would it come from the increased pressure from the heat of the candle?
Pressure is actually mostly dependant on number of molecules and is mostly independent of size of molecules (ideal gas law)... Basic combustion is Fuel+O2->CO2+H2O... If the fuel has no oxygen molecule in it, then you'll need two molecules of O2 being converted into one molecule of CO2 and 2 molecules of H2O.... Example: Fuel+2O2->CO2+2H2O. This you are effectively removing half the oxygen molecules (converting O2 into half as many CO2 molecules). But oxygen is only ~21% of air by mole fraction (number of molecules). Also some of the water will also be added to the air. Overall it would only contribute a gery small amount of decreased volume due to oxygen being consumed
The candle wic is oxidizing. Chemical reaction. What he's saying is true but I think the water level moves from the pressure change from the air in the jar getting hot and then cooling. The air is expanding and contracting.
If a building detonates, obliterating it, we say the building was destroyed. We can say that when if the total mass of the system after the explosion exactly equals the total mass of the system before the explosion. In this sense, we can say the candle actually does destroy matter by converting a small amount of what's in the system into different and less useful things. Things like neutrinos and heat because efficiency and entropy must be considered. If you have gasoline and you light it in fire, you no longer have gasoline after it all burns up. In the case of the candle, it's converting wax into air which condenses into something that is no longer candle wax.
CO2 will dissolve in water, H2O will condense. A "burning" process without heat and gas formation is needed instead like rusting steel wool - it consumes up the oxygen, so that the liquid level will rise. All you need additionally is a little patience...
Thanks for taking the time to do this experiment! Would you do the experiment again but keep the camera on for a few hours after? I'm thinking that the water vapour may condense and join the other water.
We arent creating nor destroying matter but we are rearranging it.....the water vapor condenses thereby creating a slight vacuum. Multiply it by the number if candles in the original experiment and you will see the same result..mits not expanding air
Some commenters have noted the water vapor and carbon dioxide entering the water. I am wondering about the incomplete combustion as the O2 is depleted generating carbon monoxide. Is there any way to quantify this? How would it alter the water level?
In principle the reaction COULD consume gas if all of the products weren't gasses, and it doesn't actually, but, I suspect most of the oxygen isn't consumed and the reaction stops as soon as enough CO2 builds up, so the reaction doesn't go long enough, so, in fact, yes, as you said originally, this phenomenon has to have a physical instead of chemical origin. Besides, we ca estimate how much oxygen you need for that volume of oxygen to be consumed entirely. Just as a preview of the reasoning, the reaction comes to approximately: (CH2)n + 1.5 O2 -> n CO2 + n H2O So 1.5 volumes of O2 become, very roughly, 2 volumes of H20, in the simplest version of this reasoning. Of course this isn't EXACTLY, what's happening and we are simplifying many things here, but since the volume change would be positive instead of negative, the combustion simply doesn't cut it as an explanation. It also doesn't go long enough to be. Following that equation you could roughly take a normal conditions of pressure and temperature volume and calculate via the variation how much you used of fuel and how many calories that is and a thermochemical and calorimetric analysis will shed the truth of the matter out.
You can’t create or destroy matter with a candle, but the chemical reactions that just took place displaced more water as the waterline did not return to the same hight. Remember, you has a solid be converted into a gas.
Combustion consumes oxygen through oxidation so what actually happens is that Carbon dioxide is produced, & thus the Oxygen doesn't dissappear it combines with Carbon.
The flame heats the air, the hot air expands, the expansion creates higher pressure in the glass and there for the water gets pushed down. Use a pressure gage?
The heat causes the air to expand, increasing atmospheric pressure and that pressure displaces the water. As it cools and pressure decreases, that water will rise again
Although Oxygen(02)is necessary for things to burn. The oxygen itself does not burn. It is separated and binds with the Carbon to become Carbon Monoxide.(CO).
Just use a few grams of wet steel wool and wait a day or two until it's mostly rust. The oxygen is bound to iron as Fe₂O₃. Four moles of iron (about 0.23 kg) consume 3 moles of O₂, about 72 liters. After the oxygen is bound up as solid, the number of moles of gas is 20% less. Supposing constant temperature and pressure, the volume of gas will be 80% of the original amount. The water will rise until the pressure inside the glass equals the atmospheric pressure, less a small correction for gravity. (Atmospheric pressure raises water about 30 feet before gravity defeats it). The water will rise 20% of a cylindrical bottle. If you started with pure oxygen, the steel wool would rust faster and the cylinder would end up completely full of water, unless it was over 30 feet tall. In that case, the open space above the water would contain water vapor at the vapor pressure of water.
Thank you for this experiment. I was struggling to show this. I used KOH to obasorb C02 and showed that more water goes in since potassium corbonate will be solid again. Also, people dont reallize gas cools down rapidly when flame goea off.
Science teacher here. Yeah, the flame doesn't "consume" the oxygen. The roughly 21% O2 gas in the jar reacts with the hydrogen and carbon in the candle wax (wax is a hydrocarbon) to produce carbon dioxide (CO2) and water (H2O), both of which are gases. Burning a candle actually adds gas, or mass to the existing gas, to the system. Candles going out in a closed container creates suction because hot air is less dense, and takes up more space per unit mass, than cooler air. After the oxygen has been used up in the combustion, the flame goes out and the temperature rapidly falls as the heat escapes. This causes the air in the container to shrink as its density increases, lowering the pressure in the process, causing suction.
Suction? No. As the air cools, it creates a pressure differential. The air outside the container being greater in pressure forces the water into the container until the pressure inside is equal to the pressure outside.
Suction? No. As the air cools, it creates a pressure differential. The air outside the container being greater in pressure forces the water into the container until the pressure inside is equal to the pressure outside.
@@castleanthrax1833 well, that's what suction is, a difference in internal and external pressures. When you suck on a straw, you lower the pressure inside your mouth, and in the straw, causing the atmosphere to push your drink up the straw. Suction cups are just the atmosphere pushing against a surface with lower pressure behind it.
@mscottjohnson3424 The force (in the case of the video) is coming from OUTSIDE, the container... not from inside. This is not an example of suction. There was no air removed. Suction is the removal of air. The video shows a force similar to when a plane window breaks and someone is forced or blown out the window, rather than being sucked out the window. With the equalisation of a pressure differential, the force is not suction.
Air is made of matter the same way anything else is. Matter cannot be destroyed, only transformed. If there is nowhere for the matter to go, it will stay where it is regardless of its form.
The idea is also that the hot air turned cold takes less space. Or solidify the air so it takes less space. But the flame isn’t hot enough to make the volume of either go down.
The reason people theorized like this is because this was misexplained on other channels. They would light the candle then place the glass over it. Trapping the hot air inside, resulting in the water being successful up into the glass. This example I think is much better, becaue it shows the water level lower while the candle is lit, then return to where it was originally once it goes out.
It does consume the oxygen, but that oxygen doesn't just disappear in another dimension. It's "caught up" into CO2. And it can't be lower either, because that carbon that got caught into CO2 didn't come from nowhere. It came from the candle, that now displaces less air.
I thought it heated the air inside the glass before it got a good seal, then when the air cooled it contracted creating lower pressure allowing atmospheric pressure to push more water in
If we put the glass over a separate flame, before putting it on the plate of water. Will the water level rise in the cup? (I was thinking about those Chinese TCM suctions cups. Vacuum cupping therapy.)
Not to be argumentative. But you said it’s a “closed system” a closed system does not let matter through. If it was truly closed it would not pull water from outside. So, unless I’m mistaken it is an open system.
This explanation might need some elaborating. First of all, yes it does actually consume all of the oxygen. The way you worded it, it sounded as if you were contradicting that. Secondly, when energy takes on a different form, it very often has a different volume. It isn't beyond any laws of physics to think that the volume could be different. It's just a happy circumstance that the volume is roughly the same in this case. But is it even exactly the same? These are some questions that are not answered by this video.
It is as near as dammit exactly the same. O2 plus some carbon becomes CO2. If they are ideal gases they will occupy the same volume for a given temperature. They are close enough to ideal gases for the purpose of this experiment. You can ignore the volume of the carbon, which was tiny as it was in a solid form. The water produced, once it condenses, will also occupy only a tiny volume.
Additionally it's highly unlikely that all the oxygen is actually used by the fire. A flame requires a certain percentage of of oxygen to burn and will go out when the threshold is passed, which will be long before the oxygen concentration is exhausted.
It doesn't consume all the Oxygen in the Bottle, not even close. A candel will get extinct at 15% Oxygen in the Air, and there is only 20% Oxygen in the Air. So there is only about 1/4 of the Oxygen. used up.
This video poves it is the kinetics difference between the reactants and product, open and closed atmospheres which caused the pressure difference and the ultimate cause is the consumption of oxygen but that does not mean the destruction of matter when we refer to the pressure of the container as vacuum pressure.
Candle produces heat and carbon monoxide. Some water vapor and other trase stuff. The heat expands the gas. This displaces water. The it goes out and the water comes back.
I can’t believe people aren’t born with at least this physical principle. Matter cannot be created or destroyed unless slipped into another dimension with awesome energy.
We used to do a trick with a shelled hard boiled egg and a milk bottle. You would light a piece of paper and drop it into the bottle. Then we’d place the boiled egg on the mouth of the bottle. As the fire consumed the oxygen in the bottle it would suck the egg into the bottle. So why doesn’t the water rise more?
The fact people have a hard time understanding this is fascinating. Hot gasses take up more volume. When those hot gases, cool down, there is less volume. Thus in his first experiment when the hot gas is cool down when the lid goes on, there is less volume and the atmosphere pushes the water into the container. It really that simple. there are much more complicated things in physics… I love your videos, very good job❤
No. What you say doesn't really make sense either. Gases fill the volume of a container so they don't take up a constant volume.
However, for the same moles of gas, the pressure the exert will be inversely proportional to the volume they currently occupy. So expanding a gas without adding more molecules will drop the pressure. But increasing the temperature increases the pressure, so in this case it will cause an expansion as it can push against the water surface more than the atmosphere. This pressure drops when it cools back down and goes back to the original volume.
@@kbee225 your explanation is more technical, thusly, It is a better explanation than mine. However, the gases in the container do take up a specific volume once you compress them to a certain point. Absent the compression they only cause a pressure differential depending on the conditions in said container. The burning candle replaces the oxygen it reacts with, with carbon dioxide and various other compounds from combustion, so in the end, the pressure is directly related to the temperature and thusly the volume of said gasses right? I did not major in physics, but I think me and you are saying the same thing, are we not?
@@jacksondodd8835I think the issue is that you're trying to say -
"Matter in = matter out and
Temperature follows the constants." in 500 words so you sound like a PhD when this is actually an entry level observation. If anyone didn't understand - the video explains it. If you want to teach, explain something the video doesn't.
@@KrakenIsland64 so if you were going to explain to a child, the phenomenon going on in his video, you would say what you said? Matter in matter out, temperature follows Constance?
Do you think a kid would be able to understand that? if you said that to a child and didn’t show them the video, could they re-create the experiment? but yet this is a phenomenon that a kid could understand it is not complicated physics but congratulations, your explanation made it complicated It needs lots of context to understand in the specifics of this experiment
. My explanation might be long in words, but it is easy for somebody to visualize . You would need to know quite a bit of physics to understand your explanation. -- Edit : I reread your response and I see what you are saying by adding something new but I was not trying to add anything new. I was trying to explain to people on here who had commented who couldn’t understand the basic level much less your explanation, my friend.
We recreated the experiment in a closed system - is impressive enough!
I love the fact that your videos are one shot with the explanations timed with the experiment. Makes for great viewing, thanks!
Its cool that you made a follow up video, thank you sir.
Maybe it could be instructive to burn steel wool under the glass. It binds the oxygen as rust isntead of releasing it as CO2. Should you get a different effect, especially after cooling down?
That would be a nice counter-point to his last statement. No, indeed you can't create or detroy matter with a candle but you can change the state of matter and this would affect the pressure.
Thanks! Always wanted to see that experiment done. You can't create or destroy matter with a candle, but you can increase the number of molecules in the gas, increasing the volume consequently.
The fuel of the candle is a hydrocarbon, made up mainly of hydrogen and carbon. Each molecule of O2 in the initial gas will produce either one molecule of CO2 (without changing the volume - number of moles) or two molecules of H2O, increasing the number of moles in the gas (and volume, consequently). The water level seems to return to its initial position only because of the condensation of a significant part of the water vapor when it comes into contact with the water and the glass wall. The thickness of the water level mark in the glass helps to hide any discrepancy between initial and final volumes.
Gas pressure is not dependent on the TYPE of gas you have. It only depends on the TOTAL AMOUNT of gas molecules you have. So if you use up six O2 molecules to burn the candle, resulting in three new CO2 and three new H2O molecules... you still have a balanced number of SIX total gas molecules produced as you use up the original SIX gas molecules. So the gas pressure before = the gas pressure after. And it's the gas pressure that balances the water level. Thermal expansion, heating the air in the jar from the flame, has a bigger impact on the water level than the chemical reaction of the oxygen with the candle. Hot air is higher pressure so the water level drops. Cooler air is lower pressure so the water level rises as the candle extinguishes and the air in the jar cools down.
C25H52 + 38 O2 = 25 CO2 + 26 H2O
C25H52 + 25.5 O2 = 25 CO + 26 H2O in both scenarios, we started with 38 or 25.5 gas molecules, ended up with 25 gas molecules. Not to mention CO2 would be absorbed into water at a muncher higher rate.
Almost correct. 1) it’s not the amount of gas that matters, but the number of molecules. 2) this is an approximation for perfect gases that assumes a gas molecule occupies no volume and that disregards any attractive / repulsive forces between gas molecules.
why do you think H2O cannot be in vapor form?@@honggao9610
Remember to make sure your reaction is balanced. 6O2 cannot turn into 3CO2 and 3H2O as that would require 4.5O2 molecules. Other than that you are correct. As well it is good to remember that the water molecules can condense which lowers the total number of molecules in gas phase
@@jaredrigdon3582i believe the point was that it was the gas molecule counted as opposed to the accuracy of the chemical reaction.
O2, becomes CO2, amount of molecules is the same and gas takes always same space IF it has same temperature. In this case candle makes gas a bit warmer, which causes it to expand, push a little water out and to create water vapor. When temperature will balance with outside, water level will go to original position.
nah. Candle is not C. Candle is close to C25H52. The H in candle will bond with O2 and form H2O which after cooling down is a liquid. C could burn completely and form CO2 and incompletely and form CO. However the is just too much H element. C25H52 + 38 O2 = 25 CO2 + 26 H2O
C25H52 + 25.5 O2 = 25 CO + 26 H2O. In both reactions, you have less gas molecules after the reaction thus the amount of gas molecules reduces in the closed system.
@@honggao9610the C in CO2 and H in H2O were not in gas form, so you have roughly the same amount of gas volume. Some of the water will condense, but either way most of the air in the glass is nitrogen that doesn't react at all.
@@klh_io you don't seem to understand. According to the ideal gas question, it doesn't matter what the molecule is, all that matters is how many molecules there are (moles). So if I start with 38 molecules of gas (O2) like honggao mentioned above, and go to 25 molecules of gas (CO2) since the water will most likely fully condense (assuming the air space in a closed container with water should already have 100%RH) , then you see a drop in pressure, and that is directly due to combustion. @honggao9610 is correct.
It’s the laws of conservation of energy/mass. Energy/mass can neither be created nor destroyed, only changed. The oxygen is transformed into carbon dioxide and water vapor, equaling a net zero change in water level. Neither mass nor energy of that closed system are added or removed, only rearranged.
It's also a good demonstration on why one's "gut" instinct isn't a substitute for investigation and experimentation.
Now try it with steel wool instead of a candle
I kinda want to see this as well considering steel gains mass from burning
I would expect a drop in pressure if this is the case. Assuming the iron can keep reacting to deplete the oxygen levels to near zero. Then if there is enough iron to react, the pressure should drop by 20% as this is the partial pressure of O2 in our atmosphere.
I'm waiting for this follow up 😁
In that case the amount of gas would reduce, because buring iron forms iron oxide, which is a solid instead of a gas. With the candle, carbon in the parrafin is combining with the oxygen to form carbon dioxide, another gas, and for each mole of O2, you get one mole of CO2, so you end up with the same total volume of gas in the end. Technically there is a little water vapor as well, but that quickly condenses onto a liquid on the glass.
@@RazzleberryHazeit gains mass because the end product is the steel wool mixed with the oxygen it pulled from the air. And unlike a candle where the products from combustion disperse in the air the products from steel wool remain solid. It's basically just rust.
The candle wax is mostly hydrocarbon when it burns completely there should be some volume change.
23N2(g) + 6O2(g) + 4(CH2)n(s)-> 23N2(g) + 4CO2(g)+ 4H2O(l)
Or about 6%.
Assuming the room is 20°C and the air is at 50% relative humidity then it can hold about another 1% of water vapour before it condenses into the droplets on the glass.
The flame is yellow because soot is glowing yellow hot. Soot is only formed when there is incomplete combustion. Two molecules of carbon monoxide (CO) as it cools disproportionates into soot (C) and carbon dioxide (CO2), so there is probably some carbon monoxide in the gas.
I'm wondering where you get the 6% from?
@jeroennoordkamp3416 33 molecules (23+6+4) of gas initially reduced to 31 molecules (23+4+4) of gas. 1 ot 33.333... is 3% so 2 in 33 is a little over 6%
Doesn't condensation occur when relative humidity is at 100%? Relative humidity being at any given temperature the amount of water the air can hold.your claim that condensation would occur at 51% humidity just seems implausible.
Irrelevant?
@@bengriffin4027the fuel is not a gas. It's 6 moles of gas turned into 8 moles, so 33% more gas.
Each O2 becomes CO2 or 2H2O. So overall gas increases. Bu H20 can liquefy. So once temp and humidity are returned to initial values, there should be slightly less total gas.
Unless there was incomplete combustion, 2C+O2->2CO, that would give 2 moles of gas for every one mole of O2 consumed
Yeah. Given that the fuel is paraffin, you get about 34% more gas than the gas (O2) used, but only 65% of the O2 used as CO2. I imagine that a fair amount of the water stayed gaseous because otherwise it'd appear that the volume should be 65% of what it was. Or maybe you get a lot of CO as well.
@domvasta Yes, that is a good point. The more I think the more factors I see I missed.
There would also be some carbonised soot that only loses H but the C doesn't react.
Also, CO2 will dissolve into the water with a higher frequency than O2.
And the volume of the candle is reduced.
I guess this is why physicists love frictionless spheres, not cows.
@@Tomyb15A candle won't burn atmosphere to 0% O2. There are (preventive) fire suppression systems for datacenters and libraries that reduce oxygen to 15% to prevent accidental fires. I assume a candle is more effective and will still burn at 15%, but certainly not down to 0%.
I just watched the initial video a few hours ago with my friend. We had come to the agreement that you were right basing our arguments on the principle of conservation of matter. Thank you for this follow-up. Solidified our arguments
Wow this makes so much sense! And "you can't create or destroy matter with a candle".... well said!
Except apart from that he's wrong. It's to do with hot gas expansion & partial pressures of CO2 & O2
I believe that if you used steel wool water lever would rise as rust is a solid do much denser than oxygen
Correct. True inquirers will trust you but verify!
Basic chemistry. You cannot create nor destroy anyone element. However you can convert elements from one to another combining and dividing creating new compounds with the addition and release of energy.
Nice experiment! The last sentence implies a misconception: You dont have to destroy or create matter to make the waterlevel rise above the initial hight. You would just need a reaction that chnages the volume (not the mass).
Astonishing You are a BOSS
That candle experiment is wonderful
Also the net mol values of gas are the same, since we are not working in extreme conditions we can assume ideal gas behavior where pressure=(nRT)/V, all the values thus remain constant
Now, I have wondered how the candle is supposed to "take" the oxygen as paraffins react to water and carbon dioxide (in case od ideal combustion). Thanks alot for your video and explanation.
By the ideal gas law, PV =nRT or assuming the temperature and pressure are constant when equilibrium reestablishes after the jar cools back down, the volume will depend only on the ratio of number of moles of gas present before and after burning - since RT/P is constant. The effect of the temperature increase while the candle burns can likewise be calculated. No reference to the conservation of mass required, just a basic understanding of chemistry and physics. But a great demonstration which gets people reasoning, well done
The water level changes due to the expansion of hot gas, but after cooling, PROVIDED THE SYSTEM IS ACTUALLY CLOSED, you will not end up with any more or less gas. Literally conservation of matter, the water level changing has everything to do with heat and gas pressure from expansion, not from total amount of gas changing.
A very nice way to say "no, shut up and let the smart people talk" lol
This is a nice way of testing a hypothesis for people so they can learn, it's not "shut up" it's "let's see how it works"
@@bujustic meh, that's not as funny
@@Willy_the_gunslingin_studentOD why telling people to shut up would be funny in first place? Lol
@@luisrocha26 it's not, doing it indirectly is. It's comedy, you may not think my take it funny and it's okay to be wrong, that's how we learn
Spray inside the cylinder and ignite. The water will reach to the top instantly
It's not create or destroy matters
It's changing the Atmospheric pressure because of the content in the closed system like conversion of the air(O2) into something different
The density also matters
Candle wax molecules consist of H and C atoms, with approx. twice the number of H atoms as C atoms. The O2 molecules are used to create both CO2 and H2O, spreading the available O atoms over both. The result is that the number of gas molecules created is about 33% more than the O2 molecules used. Air consists of approx. 20% oxygen.
Therefore, if all oxygen was used, the air should expand in volume with about 7%
Now, we can clearly see condensation on the glass, so part of the water condenses out.
But are you sure that the expansion is only because of the heat?
The candle pushes the air out by heat expansion then it rapidly shrinks sucking the water in
exactly, this is physics 101, not chemistry at all.
Remember volume is not a comserved quantity. The mass of the system is constant but mass from the candle goes into the gas phase which changes the total volume. Since density is normally constant you would think volume is conserved but you cannot make that assumption when reaction or temperature change is involved as is shown in this system.
Combustion reaction is equimolar, same moles on each side, same amount of gas, same pressure (if ideal gas but it's pretty much ideal at 1 atm) so we would never expect the pressure of the gas to go down in fact we expect the gas to heat up from heat of reaction and equilibrate at a larger volume. I remember coming across this problem a while ago but I've never seen one where the entire volume of the gas is contained like this! Good experiment!
You should do one with steel wool burning since in that reaction there is gas absorbed, it would be interesting to see whether the heating effect from the combustion or the removing of oxygen would win. When the temperature returns to normal the water level should actually go up. Bringing a monometer in could actually help explain it as well.
In this case it's not the same amount of gas, as also some water vapor is formed which condenses quickly to liquid....
Would be the same wit Steel wool.
Remember there is only 20% of Oxygen in the air, and the fire will get extinct at about 15%. So the effect would still be low.
However this effect is irrelevant in comparison to the expansion by heating.
@@thomasflototto9064 I understand the mechanics I'm just interested. I guess you can speculate the heating is more effective but what I want to do is calculate which one will win, which you are right it does but I want to see this guy do it with his kit.
@@thomasflototto9064 also the water level barely changes if at all so the condensing water has very little effect on the end result. With the steel wool the end result will have the water level rise as long as the system isn't adiabatic.
This is pressure working on the system. Too much pressure inside pushes water out. And when the candle is put out, the air cools thus reducing the pressure and water is sucked back in
Well, suction can be achieved a few ways, voiding the gas Inside or heating or cooling which is the case here. The air inside was heating until the fire went out then it cooled and sucked in.
Oxygen only accounts for 21% of the air volume at sea level... even burning all of the oxygen out still leaves almost 80% of the air. Now, consider that burning the candle releases gasses back into the container. Not really gaining or losing much at the end of it.
The H element in the candle will need to bind with O2 as well…. C25H52 + 38 O2 = 25 CO2 + 26 H2O. Gas molecules started as 38 + other, ended as 25 + other. So it reduced. Real reason water level didn’t not go up is. O2 is only 21% of air, and the candle stopped burning properly only consumed properly less than 10% of O2. 38 to 25 is a minor reduction, so probably less than 2-3% volume reduction which can’t be observed with your set up.
Well done for demonstrating. This is why I love science, it doesn't make claims, it makes observations and then checks ❤
About that last thing you said, that you can't create or destroy matter with a candle. That is true, but you can turn one substance into another through a reaction, where the product has a different density at the same temperature and pressure. If the jar was pure oxygen and hydrogen and you somehow prevented the jar from blowing up in your face after lighting the candle, you would find a jar full of gases turn into a jar with water vapor. That water vapor will try to condensate and turn into a tiny amount of liquid water and a whole lot of vacuum that will suck the water from below.
Sure, in this experiment it's just heat, cause the combined products (CO2 + H2O) ain't that much more dense in room temp than the ingredients (O2 + carbon-containing fuel in the candle), but the idea that it can't be the consumption of oxygen into another compound - not entirely nonsensical.
That's true. A very correct explanation. The amount of carbon dioxide and water vapour created is almost equal to the amount of oxygen used up. The partial vacuum created inside is due to two factors. 1. Initial Expansion of gas due to heat which pushes the gases out of the plate and then when flame goes out the gases contract and pull in some water.
2. Condensation of water vapour into water on the sides of the glass tumbler.
These two phenomenon combine to create partial vacuum which ultimately pulls in water.
If solely consumption of oxygen were the reason then irrespective of the number of candles you use the total rise of water would have remained steady at about one fifth the height of the glass tumbler. But if you increase the number of candles the rise of water will be more.
Hence the explanation here is correct.
I never thought id find a new science guy randomly on shorts. But here we are... time to binge!
You can’t create or destroy matter (except when it turns into energy) but you can do a chemical reaction which changes the volume from beginning to end.
Chemical reactions actually cause a gain or loss of mass proportional to the energy produced or consumed. Energy is the constant that can’t be changed.
Chemical bonds have tiny amounts of mass that are either destroyed to produce energy or created to store energy. Most chemical reactions do both but the sum of mass changes will be your energy released.
@@Playingwithproxies
E=m*c^2
=> m=E/c^2 .
c^2=9*10^16 m^2/s^2.
So the factor between Energy and mass is extremely large. And thus if the candle loses 100J of Energy to environment via heat, it will only loose 1.1*10^(-15)Kg of mass.
Thats like nothing. Nobody can measure the mass of a candle down to this accuracy.
If it wasn't so explosive, an atmosphere of hydrogen and oxygen would prove that.
First a rapid explosion, then almost a vacuum... because the gasses are way less dense than the water they turn into.
I missed that point. He was referring to the no such thing as a free lunch law of thermo. But yes as you say, that's referring to energy and not matter.
Thank you sir.
in the other experiments where the water level rises, it is because in those scenarios the air inside is heated enough that some of the air actually bubbles out the bottom. That part of the other experiment is carefully engineered out of this experiment.
Ok,but what you are ignoring, is that volume is not conserved in a chemical reaction, even if temperature is the same.
In this case a simplified reaction equation is:
C+O2 -> CO2.
Now we got one O2 molecue plus one Carbon molecule at the beginning. In the End we have one molecule of CO2. The CO2 will have the same volume as the initial O2 after the reaction, as PV=NkT.
But the Carbon is now part of it. The Carbon,which has used extra space before, now does not use extra space!
So the volume still decreases approx. by the burned up volume of the candle.
This would be true,if the candle was madw out of carbon..However it is made out of wax, so it produces also water and some other stuff. So if you consider this, then in the end the volume might even be bigger than before. I dont want to calculate this, but i just want to point out, that while mass is conserved, volume isnt.
Also to do with partial pressures & hot gas expands
Changing the pressure dosent require creating or destroying matter though
The energy being used is within the container, it didn’t lose or gain it just explained as far as it could and then contracted back to even the pressure that was used
One thing is talking about consumption of oxygen and other thing is talking about how temperature of gases expand or contract them.
Mate ur content is the best 🤙
Thank you for saying with a candle... but even more accurately with this set up...
Laws of thermodynamics....the airline cooling and shrinking and pulling a vacuum pulling the water upward...I think thats correct
1. the candle does consume most of the oxygen. 2. it does create co2 and h2o but the water vapor shold turn liquid as their boiling point is way above room temperture. the lower than atmospheric pressure does help sustain more water vapor than in an open container but still.
you can actually see it creates more gass, as the water level goes from the top of the mark on the glass to it's buttom. creating and destroying matter got nothing to do whatsoever with that experiment. it is about creating or destroying volume by transfering matter from solid to gass state. you can create or destroy volume without creating or destroying matter. for example - any explosive creates tons of volume without creating or destroying matter.
CxHy(s)+ (x + y/2)O2(g) -> xCO2(g) + yH2O(g)
Initially, you'd expect the gas to expand as it's both heated and transformed into (y/2) more molecules. Then it should contract as H20 condenses, CO2 dissolves into the water, and after the flame goes out, the gas cools. That assumes complete combustion, which the yellow flame indicates is not the predominant reaction. Solid carbon and gaseous carbon monoxide are also produced, stretching the O2 reactant further.
This is a pressure related phenomenon. The candle cant burn a large quantity of oxygen anyway before the concentration drops below a critical threshold.
The volume difference assuming constant temperature should be small in comparison to the effect of the pressure increases impact.
Before you take any actions the water level in the jar was higher than the ordinary level of water in the tray! How did you get water to that higher level in the jar than the surrounding, in the tray?
I appreciate the explanation, but I'm feeling like there might be something I'm missing or a trick involved. Could you please clarify that?
Could of been a couple tricks. Easiest probably being to lower the air pressure in the cup by removing some air, thus sucking the liquid up higher into the cup. A small hose could accomplish just that.
@@censorsstarveor he heated the air in the jar, so that when it cooled down, it contracted, allowing the outside air pressure to push the water level up
The only reason why the water level rises in some experiments is because they don't have the cup in the water while they light it they let the candle burn with a space underneath for gases to escape and when the air is heated in the cup and then you extinguish the candle then place it back in the water it will cool and suck water in. It's sad how dumb people are now
This is a cool modification of the bar trick. And a nice explanation for the new circumstances
1 mol of gas takes up 22.4 Liters of space. No matter what gas it is at Atmospheric pressure. If The reaction that takes place converts 1 mol of o2 to 1 mol of Co2, no change in volume should take place other than that which increases the temperature and pressure. There is also vapor which undergoes a phase change
@guodlca you don't know what the chemical structure of the wick and wax are. You can't do the balanced reaction without knowing. That's why I generalized.
@guodlca right..I mentioned the vapor which if it condensed, wouldn't add to the volume
So in the usual experiment is that the expanding air actually leaked out of the glass from the bottom and can't get back in. When the air cools from the candle dying, the air volume goes down and the water take its place.
Precisely, from V amount of oxigen burning a paraffin oil or vax, you get 2/3V carbon dioxide and 2/3V water. It is more than the initial gas (in terms of number of molecules, and in terms of volume on the same temperature). If water condeses, it is less than the initial gas.
You cannot destroy matter in this way, but in gases the number of molecules matters, not the weight or the number of atoms within the molecules
.
You can't create or destroy matter, but the reactions can create new compounds with different densities to the original ones. Respiration is a prime example of that. Could that be where the confusion lies or would it come from the increased pressure from the heat of the candle?
Do the experiment with steel wool. The iron absorbs the oxygen, I imagine after the initial expansion from heat, it would contract slightly.
Pressure is actually mostly dependant on number of molecules and is mostly independent of size of molecules (ideal gas law)... Basic combustion is Fuel+O2->CO2+H2O... If the fuel has no oxygen molecule in it, then you'll need two molecules of O2 being converted into one molecule of CO2 and 2 molecules of H2O.... Example: Fuel+2O2->CO2+2H2O. This you are effectively removing half the oxygen molecules (converting O2 into half as many CO2 molecules).
But oxygen is only ~21% of air by mole fraction (number of molecules). Also some of the water will also be added to the air. Overall it would only contribute a gery small amount of decreased volume due to oxygen being consumed
The candle wic is oxidizing. Chemical reaction. What he's saying is true but I think the water level moves from the pressure change from the air in the jar getting hot and then cooling. The air is expanding and contracting.
If a building detonates, obliterating it, we say the building was destroyed. We can say that when if the total mass of the system after the explosion exactly equals the total mass of the system before the explosion. In this sense, we can say the candle actually does destroy matter by converting a small amount of what's in the system into different and less useful things. Things like neutrinos and heat because efficiency and entropy must be considered. If you have gasoline and you light it in fire, you no longer have gasoline after it all burns up. In the case of the candle, it's converting wax into air which condenses into something that is no longer candle wax.
@guodlca normal chemical reactions are just one of many ways to produce neutrinos. Neutrinos are USUALLY produced only through nuclear reactions.
@guodlca try looking for pions and other mesons.
CO2 will dissolve in water, H2O will condense.
A "burning" process without heat and gas formation is needed instead like rusting steel wool - it consumes up the oxygen, so that the liquid level will rise. All you need additionally is a little patience...
Thanks for taking the time to do this experiment! Would you do the experiment again but keep the camera on for a few hours after? I'm thinking that the water vapour may condense and join the other water.
Subscribed.. That was good stuff 👍
Nice experiment to prove a point
We arent creating nor destroying matter but we are rearranging it.....the water vapor condenses thereby creating a slight vacuum. Multiply it by the number if candles in the original experiment and you will see the same result..mits not expanding air
Some commenters have noted the water vapor and carbon dioxide entering the water. I am wondering about the incomplete combustion as the O2 is depleted generating carbon monoxide. Is there any way to quantify this? How would it alter the water level?
Heat expands the gasses
In principle the reaction COULD consume gas if all of the products weren't gasses, and it doesn't actually, but, I suspect most of the oxygen isn't consumed and the reaction stops as soon as enough CO2 builds up, so the reaction doesn't go long enough, so, in fact, yes, as you said originally, this phenomenon has to have a physical instead of chemical origin. Besides, we ca estimate how much oxygen you need for that volume of oxygen to be consumed entirely.
Just as a preview of the reasoning, the reaction comes to approximately:
(CH2)n + 1.5 O2 -> n CO2 + n H2O
So 1.5 volumes of O2 become, very roughly, 2 volumes of H20, in the simplest version of this reasoning. Of course this isn't EXACTLY, what's happening and we are simplifying many things here, but since the volume change would be positive instead of negative, the combustion simply doesn't cut it as an explanation. It also doesn't go long enough to be.
Following that equation you could roughly take a normal conditions of pressure and temperature volume and calculate via the variation how much you used of fuel and how many calories that is and a thermochemical and calorimetric analysis will shed the truth of the matter out.
It simply is a matter of temperature, not about consuming oxygen
Seems like the heat just expand the gas, which is why it lowered. Then it cooled and returns to its original volume.
Exactly.
You can’t create or destroy matter with a candle, but the chemical reactions that just took place displaced more water as the waterline did not return to the same hight.
Remember, you has a solid be converted into a gas.
Combustion consumes oxygen through oxidation so what actually happens is that Carbon dioxide is produced, & thus the Oxygen doesn't dissappear it combines with Carbon.
The flame heats the air, the hot air expands, the expansion creates higher pressure in the glass and there for the water gets pushed down. Use a pressure gage?
The heat causes the air to expand, increasing atmospheric pressure and that pressure displaces the water. As it cools and pressure decreases, that water will rise again
Although Oxygen(02)is necessary for things to burn.
The oxygen itself does not burn.
It is separated and binds with the Carbon to become Carbon Monoxide.(CO).
@guodlca The oxygen is not consumed it either changed state or bonds to other elements.
The same amount of oxygen is still present.
Just use a few grams of wet steel wool and wait a day or two until it's mostly rust. The oxygen is bound to iron as Fe₂O₃. Four moles of iron (about 0.23 kg) consume 3 moles of O₂, about 72 liters.
After the oxygen is bound up as solid, the number of moles of gas is 20% less. Supposing constant temperature and pressure, the volume of gas will be 80% of the original amount. The water will rise until the pressure inside the glass equals the atmospheric pressure, less a small correction for gravity. (Atmospheric pressure raises water about 30 feet before gravity defeats it).
The water will rise 20% of a cylindrical bottle.
If you started with pure oxygen, the steel wool would rust faster and the cylinder would end up completely full of water, unless it was over 30 feet tall. In that case, the open space above the water would contain water vapor at the vapor pressure of water.
This is lavoisier's law, folks! "Nothing is created or deetroyed, everything is transformed."
Thank you for this experiment. I was struggling to show this. I used KOH to obasorb C02 and showed that more water goes in since potassium corbonate will be solid again. Also, people dont reallize gas cools down rapidly when flame goea off.
Stoichiometry for the win!
Science teacher here. Yeah, the flame doesn't "consume" the oxygen. The roughly 21% O2 gas in the jar reacts with the hydrogen and carbon in the candle wax (wax is a hydrocarbon) to produce carbon dioxide (CO2) and water (H2O), both of which are gases. Burning a candle actually adds gas, or mass to the existing gas, to the system.
Candles going out in a closed container creates suction because hot air is less dense, and takes up more space per unit mass, than cooler air. After the oxygen has been used up in the combustion, the flame goes out and the temperature rapidly falls as the heat escapes. This causes the air in the container to shrink as its density increases, lowering the pressure in the process, causing suction.
Suction? No. As the air cools, it creates a pressure differential. The air outside the container being greater in pressure forces the water into the container until the pressure inside is equal to the pressure outside.
Suction? No. As the air cools, it creates a pressure differential. The air outside the container being greater in pressure forces the water into the container until the pressure inside is equal to the pressure outside.
@@castleanthrax1833 well, that's what suction is, a difference in internal and external pressures. When you suck on a straw, you lower the pressure inside your mouth, and in the straw, causing the atmosphere to push your drink up the straw. Suction cups are just the atmosphere pushing against a surface with lower pressure behind it.
@mscottjohnson3424
The force (in the case of the video) is coming from OUTSIDE, the container... not from inside.
This is not an example of suction. There was no air removed.
Suction is the removal of air.
The video shows a force similar to when a plane window breaks and someone is forced or blown out the window, rather than being sucked out the window.
With the equalisation of a pressure differential, the force is not suction.
Very nice experiment.
Air is made of matter the same way anything else is. Matter cannot be destroyed, only transformed. If there is nowhere for the matter to go, it will stay where it is regardless of its form.
Very good demo.😊
The idea is also that the hot air turned cold takes less space. Or solidify the air so it takes less space. But the flame isn’t hot enough to make the volume of either go down.
Balanced reality. 😎
The reason people theorized like this is because this was misexplained on other channels. They would light the candle then place the glass over it. Trapping the hot air inside, resulting in the water being successful up into the glass. This example I think is much better, becaue it shows the water level lower while the candle is lit, then return to where it was originally once it goes out.
The heat exchange is where the vacuum come from. When the hot air shrinks when it becomes cold
It does consume the oxygen, but that oxygen doesn't just disappear in another dimension. It's "caught up" into CO2. And it can't be lower either, because that carbon that got caught into CO2 didn't come from nowhere. It came from the candle, that now displaces less air.
I thought it heated the air inside the glass before it got a good seal, then when the air cooled it contracted creating lower pressure allowing atmospheric pressure to push more water in
If we put the glass over a separate flame, before putting it on the plate of water.
Will the water level rise in the cup?
(I was thinking about those Chinese TCM suctions cups. Vacuum cupping therapy.)
It's to do with hot gas expansion then cooling & also the partial pressures of CO2 & O2
Not to be argumentative. But you said it’s a “closed system” a closed system does not let matter through. If it was truly closed it would not pull water from outside. So, unless I’m mistaken it is an open system.
This explanation might need some elaborating. First of all, yes it does actually consume all of the oxygen. The way you worded it, it sounded as if you were contradicting that. Secondly, when energy takes on a different form, it very often has a different volume. It isn't beyond any laws of physics to think that the volume could be different. It's just a happy circumstance that the volume is roughly the same in this case. But is it even exactly the same? These are some questions that are not answered by this video.
It is as near as dammit exactly the same. O2 plus some carbon becomes CO2. If they are ideal gases they will occupy the same volume for a given temperature. They are close enough to ideal gases for the purpose of this experiment. You can ignore the volume of the carbon, which was tiny as it was in a solid form. The water produced, once it condenses, will also occupy only a tiny volume.
@@tortinwallits not as simple a calculation withnour knowing what exactly is burning
Additionally it's highly unlikely that all the oxygen is actually used by the fire. A flame requires a certain percentage of of oxygen to burn and will go out when the threshold is passed, which will be long before the oxygen concentration is exhausted.
Energy doesn't take on a different form. Matter does.
It doesn't consume all the Oxygen in the Bottle, not even close.
A candel will get extinct at 15% Oxygen in the Air, and there is only 20% Oxygen in the Air.
So there is only about 1/4 of the Oxygen. used up.
This video poves it is the kinetics difference between the reactants and product, open and closed atmospheres which caused the pressure difference and the ultimate cause is the consumption of oxygen but that does not mean the destruction of matter when we refer to the pressure of the container as vacuum pressure.
Thanks for reminding us of something most people learned in 1st grade. Wow
Lol ok buddy, sure ya did😂
You don't need to change amount of matter to change gas volume. You only need to change the species number of moles, which is totally possible.
So the densities of the new substances are similar? Otherwise the volume occupied could change in theory?
Can you do the experiment with some pH indicators in the water? I wonder if some of the CO2 will form H2CO3, decreasing pH.
Wouldn’t the heat from the candle temporarily increase the pressure inside the glass, slowly cooling and returning the pressure back to normal?
Candle produces heat and carbon monoxide. Some water vapor and other trase stuff. The heat expands the gas. This displaces water. The it goes out and the water comes back.
I can’t believe people aren’t born with at least this physical principle. Matter cannot be created or destroyed unless slipped into another dimension with awesome energy.
I had always assumed, from high school physics knowledge, that in a closed system like this, the only thing lost is light and heat.
We used to do a trick with a shelled hard boiled egg and a milk bottle. You would light a piece of paper and drop it into the bottle. Then we’d place the boiled egg on the mouth of the bottle. As the fire consumed the oxygen in the bottle it would suck the egg into the bottle. So why doesn’t the water rise more?