Thank you! After watching this, I did 3 Hess's law questions on Combustion and 3 on Formation. And 1 on reaction and I got them all right. I didn't have a clue about them before I watched this video! x
i know im 6 years late here but I'm so confused, I've finished year 11 and I'm trying to teach myself the AS portion of the chem a level from your vids and so far I'm doing great but this hit me like a tonne of bricks. thankyou so much for the time you put into these though!
Man hats off to you my teacher at school is terrible at teaching enthalpy she took like 7 lessons to teach the whole energetics whereas it takes 3 lessons to do a whole topic and she cannot explain the simplest thing man thanks a lot Appreciate your help keep it up your an amazing teacher
just gonna drop a message to say how much all parts have helped me understand the topic as a whole!! leaving this here so i can come back and see how i am in the future because at the moment i have no idea what i’ll be doing😪
Thanks soo much for your videos, it has been very helpful, my teacher goes very fast at school and your videos helps me understand it much better, thanks!!
sam09 It's tricky to keep the pace sometimes in class, particularly with so much content to cover (I'm sure some of my students would say my pace is a little quick at times!). It's definitely worth having a word with your teacher after the lesson one time, just to let him/her know that you find the pace a bit quick and ask if they could just slow it down a touch!
This video has saved me! After my lessons, reading the textbook, homeworks and searching on the Internet I still could not understand Hess' Law at all! I now understand it completely in less than half an hour! Thank you Mr Rintoul! :)
Could you go over finding enthalpy change of formation from enthalpy change of combustion? I have it in my text book and I cannot get my head around it! You're videos are actually saving me! No teacher until the start of this year (2016) and missing so many lessons due to clashes but these help me out so much!!
Ur an actual saviour and genius to how u managed to get all that detail into one video im baffled my teachers at school spent an hour to tesch us and u managed to get the same amout of content in 23 minutes im shook😭😭😭
Thanks to your videos I undestand chemistry- you are honestly the best teacher. Thankyou so much, if I get into medical school it will be because of your amazing work. :)
Hi, great set of videos, massively appreciate you putting in the effort to make them. Just to add a little bit more (basically the easy method)- hope you don't mind checking if this is right and correcting me where necessary: if you have enthalpy changes of formation: enthalpy change = sum of enthalpy change of formation of products - sum of enthalpy change of formation of reactants if you have enthalpy changes of combustion: enthalpy change= sum of enthalpy change of combustion of reactants - sum of enthalpy change of formation of products
Hi and thanks for the comment! You are absolutely correct. I don't like to simplify it like that purely because I think it takes away from the understanding, and I have seen a question in the past that actually gave a cycle to calculate a value from. But, in 99% of the cases, your method will work perfectly (and is much easier!).
There's a much easier way to do this: If you are given a DeltaHC values then: enthalpy change = Sum of rectants - sum of products If you are given a DeltaHF values then: enthalpy change = Sum of products - sum of reactants Sorry I couldn't explain it that well. Its hard to type it lol. Hope it helps though!
Abid Ali You are correct. BUT, this doesn't show any understanding of the cycle. Plus, if a question comes up that isn't quite as straight forward, this method will scupper you! I will also suggest that you go for a good understanding rather than trying to learn tricks to get there quicker. That said, it is quicker and for some people it might be a better option!
thank you so so so much! i was just about ready to give up on this stuff but your video has really helped! I can't keep going back to my teacher and asking her when i forget how to do it all so it's really helpful watching your video:)
Thankyou so much for these videos they are helping me get through as chemistry. I honestly wish you were my teacher ... thankyou so much for what you do
Do you have a patreon page or a subbable account or something? It seems unfair that I've given money to textbook companies that have helped me a TINY amount, but I haven't given anything to this channel which has helped me LOADS.
E Rintoul haha I'm sorry, I have absolutely no idea :( I know there's a website called patreon that is meant to do stuff like this, but I don't know how suitable that is for you (I also hear rumours they take a cut themselves). Maybe a justgiving page or something?
You made this chapter so damn easy, at my school i was confused af with this. I couldnt do it, it felt like i was trying to learn chinese, but after this video :D!
thank you so much for these videos!! big help :) I have a question though: when do we use the Hess cycle and when do we use the formula: enthalpy= products-reactants?
+lamis shehata Thermochemical cycles are used when formation/combustion data is given and the other is used for bond dissociation enthalpies. I think that's what you're asking...?
this video is from 2014 and its 2021 so its highly possible that i may never get the answer for this...but In which university or school do you teach? since you mentioned "my students"
got my answer so he is a Assistant Head of Sixth Form / Teacher of Chemistry in Ashville College in a town named Harrogate located in North Yorkshire, United Kingdom
Hi, how would you calculate the enthalpy change of a reaction when it provides both formation AND combustion data?? Im confused as to what directions the arror go to because one reactant has formation data with it and the other reactant has combustion data with it
When working out questions do you have to be able to construct a Hess's cycle or is that just to aid you? This is because I can work out the answer for Hess's law questions by using the "cancellation method" if you've heard of it.
+Shockz in formation they point up from the elements because the definition is "compound produced FROM its elements" whereas in combustion they point down to the combustion products because the definition is "burnt in o2 to FORM products"
+Shockz The arrows are just the arrows for normal equations. They are nothing special. If we FORM something then the elements point towards the compounds. If we BURN something then that thing is reacted with oxygen and the arrow points away from it.
9:40 So in this example, the value for the enthalpy of formation for H2 isn't given because you can't form H2 from it's constituents elements? Which is why you'd just take the value for the enthalpy of formation for ethyne only?
A much easier way to think about this without even having to draw out the thermochemical cycles is to just use: (Enthalpy of) Combustion = Reactants - Products (CRaP, Combustion is Reactants - Products) (Enthalpy of) Formation= Products - Reactants :)))
Thank you so so much these videos have been really helpful! I was wondering if you would be able to do a video on mean bond dissociation enthalpies as I struggle with calculating them. Thanks! :)
mariobros920 Thanks very much! I have a video already I believe... Try this one: ruclips.net/video/Ks1CtqsafSg/видео.html Let me know if there's anything else I can help with!
In the exam if you use the formula products-reactants or vice versa getting the same answer as you would if you used the thermocycle method would you still get all the marks? As I find the thermocycles method really confusing.
Wouldn't it be better to say that the definition of standard enthalpy of combustion as "ΔH of a substance..." rather than "ΔH of a compound"? Because you went on to use the standard enthalpy of combustion of hydrogen in your example, which is just an element. It was a little confusing ;; (Also, nice Pokemon wallpaper at 8:20 , I didn't know chemistry teachers could be cool xD)
sir could you possibly do a vid constructing hess cycles using unknowns so you are given various reactions and you construct a hess cycle from the reactions given there's nothing on youtube going through it and i cant do it please help
hey youtube.... i always get the right value but it just has the wrong sign infront of it... im talking about combustion of x given the formation value of y... or vice versa
I think you've made an error sir because isn't enthalpy of combustion is the enthalpy change when one mole of compound is burned in OXYGEN. The calculation for the enthalpy change of combustion was not rea ting with oxygen
its a triple tho. one carbon have 4 electrons in outer shell. it makes a triple covalent bond with another carbon atom and a single covalent bond with oxygen to complete its octet.
What's the difference between enthalpy of reaction formation and combustion, also why can you sometimes use enthalpy of formation to calculation enthalpy of combustion?
would it be possible if you could explain it the other method whereby you have the arrows following one direction e.g: C+O2=CO2 and then the arrows at the bottom not following the formation or combustion rules?
Sorry difficult to word it but basically there is another method i learnt whereby you don't do the combustion or formation arrows but the arrows point from left to right
Racing Knight OK, I think I might know... You can use another method where it is combustion = reactants - products and formation = products - reactants. Do you mean that?
With the thermochemical cycle at the end do you need to add oxygen to the reactants and products to make the reaction balance or does that not matter ?
PLEASEEEEE HELPPPPP when constructing the combustion cycle why does it not matter that oxygen is also part of the reaction? By the oxygen being there doesn't it change the initial reactant e.g instead of A + B ---) C + D we now have A + B + 02 ---) C + D?????
@Eliot Rintoul don't ever dream of deleting this channel you are literally a saviour and this channel is gold
hahaha at 8:19 when i saw your background i thought, what a teachery background to have, then i looked closer and realised!
tobais brown Haha, yes. I need to change that at some point...
@@MrERintoul no need to change its like a scientific background but from the pokemon world.
a chapter which took a whole half term in about 15 minutes (watching on speed 2) lol
+Sam K Niceee.
Either your teacher is shite or your class is shit, or both :P Difficult topic though
bit of both haha
I failed my energetics test just becuz of hess law and this video made me a pro.... i can again think of getting an A in my As level
the fact that i actually put it on speed 2 to consume less time just shows how sad my life is
Thank you! After watching this, I did 3 Hess's law questions on Combustion and 3 on Formation. And 1 on reaction and I got them all right. I didn't have a clue about them before I watched this video! x
Jen xX Excellent work - keep it up!
whose here is 2024 😅
Night before paper 1😭
my exam is on Thursday i’m cooked😭
@@strawberrymxlkxo shouldny it be friday? Check ur timetable
@@IValchevno im not doing the official as exam it’s just a mock the organisation of my school does😭
Could you make a video doing some exam questions using Hess' law
you sir ARE A HERO TO ME,I CANT THANK YOU ENOUGH.
Ahmed Qasim Thanks!
I've been struggling with this for a while but after watching your video I understood it straight away, thanks!!
Great videos and great pokemon wallpaper. You've helped me allot so thank you.
this topic scared me, now it just feels the simplest one.
you sir, have my respect
I've been struggling with hess' law for two terms now! Really been of great help, thankyou so much, virtual hugs to you! xx
i know im 6 years late here but I'm so confused, I've finished year 11 and I'm trying to teach myself the AS portion of the chem a level from your vids and so far I'm doing great but this hit me like a tonne of bricks. thankyou so much for the time you put into these though!
Same!!! Haha, we'll get through it :)
Why would you ever want to teach yourself AS chemistry?
Man hats off to you
my teacher at school is terrible at teaching enthalpy
she took like 7 lessons to teach the whole energetics
whereas it takes 3 lessons to do a whole topic
and she cannot explain the simplest thing
man thanks a lot Appreciate your help
keep it up
your an amazing teacher
same but its the class aswell. My class fuck about way too much lool and then we all wonder why we are on grade U's
8:19
Darwin with pokeball XD
nice wallpaper
just gonna drop a message to say how much all parts have helped me understand the topic as a whole!! leaving this here so i can come back and see how i am in the future because at the moment i have no idea what i’ll be doing😪
Thanks soo much for your videos, it has been very helpful, my teacher goes very fast at school and your videos helps me understand it much better, thanks!!
sam09 It's tricky to keep the pace sometimes in class, particularly with so much content to cover (I'm sure some of my students would say my pace is a little quick at times!). It's definitely worth having a word with your teacher after the lesson one time, just to let him/her know that you find the pace a bit quick and ask if they could just slow it down a touch!
You're the best teacher ever! I can't thank you enough, this helped me immensely
This video has saved me! After my lessons, reading the textbook, homeworks and searching on the Internet I still could not understand Hess' Law at all! I now understand it completely in less than half an hour! Thank you Mr Rintoul! :)
Could you go over finding enthalpy change of formation from enthalpy change of combustion? I have it in my text book and I cannot get my head around it! You're videos are actually saving me! No teacher until the start of this year (2016) and missing so many lessons due to clashes but these help me out so much!!
Ur an actual saviour and genius to how u managed to get all that detail into one video im baffled my teachers at school spent an hour to tesch us and u managed to get the same amout of content in 23 minutes im shook😭😭😭
I finally understand them, thank you . I don't know what I'd do without these videos !
THANK YOU SIR I JUST SAT MY ALEVELS IN MARCH BECAUSE U ARE TOO GOOD! THEY CHANGED THE SPEC JUST FOR YOU!!! UR A STAR GOD BLESS!!! U BEAUT
You have literally saved me... My teacher this year has been dreadful and I've realised how little I know, I can't thank you enough :)
i have my exams and this is what i am dependent on, you're a saviour
Thanks to your videos I undestand chemistry- you are honestly the best teacher. Thankyou so much, if I get into medical school it will be because of your amazing work. :)
Style Street Well I hope you do get into Med school! Keep working hard!!
thank you so much your videos will help me pass my as level, my teacher at school is so bad now i still have hope in scoring good in chemistry!
@8:19 Sir Darwin! Awesome video, I was really confused in class but it's all good now :)
Thank you so much!!! My teacher unsuccessfully taught this to me, but this video has literally helped me crack it in 20 minutes!!!
Sean Frost Excellent!
Hi, great set of videos, massively appreciate you putting in the effort to make them. Just to add a little bit more (basically the easy method)- hope you don't mind checking if this is right and correcting me where necessary:
if you have enthalpy changes of formation:
enthalpy change = sum of enthalpy change of formation of products - sum of enthalpy change of formation of reactants
if you have enthalpy changes of combustion:
enthalpy change= sum of enthalpy change of combustion of reactants - sum of enthalpy change of formation of products
Hi and thanks for the comment!
You are absolutely correct. I don't like to simplify it like that purely because I think it takes away from the understanding, and I have seen a question in the past that actually gave a cycle to calculate a value from.
But, in 99% of the cases, your method will work perfectly (and is much easier!).
Thanks a lot! Sitting here day before chemistry exam and had no idea about this
You doing ccea??
These videos are also applicable to other exam-boards, I do edexcel and these videos are helping a lot! many thanks!
CogWerk That's good to know!
There's a much easier way to do this:
If you are given a DeltaHC values then:
enthalpy change = Sum of rectants - sum of products
If you are given a DeltaHF values then:
enthalpy change = Sum of products - sum of reactants
Sorry I couldn't explain it that well. Its hard to type it lol. Hope it helps though!
Abid Ali You are correct. BUT, this doesn't show any understanding of the cycle. Plus, if a question comes up that isn't quite as straight forward, this method will scupper you! I will also suggest that you go for a good understanding rather than trying to learn tricks to get there quicker.
That said, it is quicker and for some people it might be a better option!
thank you so so so much! i was just about ready to give up on this stuff but your video has really helped! I can't keep going back to my teacher and asking her when i forget how to do it all so it's really helpful watching your video:)
Thank you so much for all these videos, i didn't have a clue about energetics , but now i do!
Luke Whiteside Excellent! Let me know if there's anything I can help you with.
You're a life saver. I owe you my as chemistry a level.
TheAcesM It's all down to you!
a hero in our time
OMG THANKYOU your videos save my lifeee I swear!! May the almighty bless youu and shower you with happiness
Thankyou so much for these videos they are helping me get through as chemistry. I honestly wish you were my teacher ... thankyou so much for what you do
You are an icon and a life saver- thank you so so much for this! It’s all starting to make sense 😁
Thank you this has helped so much with understanding Hess's Law. And now i feel prepared for my EMPA. :)
Fantastic! Good luck and let me know how it goes.
Do you have a patreon page or a subbable account or something? It seems unfair that I've given money to textbook companies that have helped me a TINY amount, but I haven't given anything to this channel which has helped me LOADS.
TheThingsThat IDo What do you mean...?
E Rintoul It's just these videos have been insanely helpful to me this year, I was wondering if you accept like donations and stuff?
TheThingsThat IDo Oh I see! I guess I could set something up...! I certainly don't expect money from people! How would I even do it?!
E Rintoul haha I'm sorry, I have absolutely no idea :( I know there's a website called patreon that is meant to do stuff like this, but I don't know how suitable that is for you (I also hear rumours they take a cut themselves). Maybe a justgiving page or something?
TheThingsThat IDo Justgiving is charity though isn't it? Would a PayPal link work?
Great help thank you so much. I was struggling with this topic for almost a week and this video/ playlist really helped me!!
I couldn't understand what my teacher was teaching me , But you sir taught me well.
would really appreciate if u could also solve some past papers for both as and alevel chemistry , it would really mean alot
WOW JUST WOW. I cannot thank you enough. THANKYOU A MILLION!!!!!!!!!!!!!!
pringles lover Big praise! Thanks, though, means a lot!
You made this chapter so damn easy, at my school i was confused af with this. I couldnt do it, it felt like i was trying to learn chinese, but after this video :D!
DOING MY ALEVELS IN 5MONTHS UR LIFE SAVER
I wonder if you are still active on this account. You posted this when i was year 6 and now im year 12 watching this amazing video.
I think you explained everything really well. Thank you for this video.
tdd9977 No problem!
I do not understand what you put in the boxes with arrows, where do u get those 2CO2 + 3H20 from????? Last combustion question
Thank you so so much, your videos are such a massive help, I really appreciate the effort you've gone though to make them!!!:)))
Zoe Dunnett No problem - thanks for the kind words!
It is request to you that Please make another video explaining the cycle in detail specially the part from enthalpy change of formation till end.
why we don't take in account the H2 in formation reaction and we take it in combustion reaction.?
thank you so much for these videos!! big help :) I have a question though: when do we use the Hess cycle and when do we use the formula: enthalpy= products-reactants?
+lamis shehata Thermochemical cycles are used when formation/combustion data is given and the other is used for bond dissociation enthalpies. I think that's what you're asking...?
Uv given me an extra 2 hours of sleep bless you
this video is from 2014 and its 2021 so its highly possible that i may never get the answer for this...but
In which university or school do you teach? since you mentioned "my students"
got my answer
so he is a Assistant Head of Sixth Form / Teacher of Chemistry in Ashville College in a town named Harrogate located in North Yorkshire, United Kingdom
Can you explain how to work out the enthalpy change if they mix enthalpy change of formation with enthalpy change of combustion please?
+Daniyal Shah Have you got a question like that? I'd need to see the question to be able to do it justice.
Hi, how would you calculate the enthalpy change of a reaction when it provides both formation AND combustion data?? Im confused as to what directions the arror go to because one reactant has formation data with it and the other reactant has combustion data with it
could you please make a video doing some exam questions of energetics, cause i do understand what you teach but i struggle with exam questions.
youre a life saviour, thank you so much for your effort and time
the equations on the past papers are hell of a ton harder please can you explain if they mix enthalpy of combustion and enthalpy of formation together
oh my god what thats a thing they can do?
When working out questions do you have to be able to construct a Hess's cycle or is that just to aid you? This is because I can work out the answer for Hess's law questions by using the "cancellation method" if you've heard of it.
how do you know which way the arrows have to go?
I'm pretty sure that in formation the arrows point outward towards the the original formula and in combustion it's reversed
+Shockz in formation they point up from the elements because the definition is "compound produced FROM its elements" whereas in combustion they point down to the combustion products because the definition is "burnt in o2 to FORM products"
+Shockz The arrows are just the arrows for normal equations. They are nothing special. If we FORM something then the elements point towards the compounds. If we BURN something then that thing is reacted with oxygen and the arrow points away from it.
What if we only make the ethane equation during the enthalpy change of combustion and use the reactants of that equation to find the enthalpy change?
Please make a video on enthalpy change of combustion by using formation data and enthalpy chanfe of hydration by using an anhydrous salt
Thanks alot for your effort. I appreciate it. very well explained!
Ayush Acharya No problem!
How come you did not switch the - for a + in the other calculation the enthalpy of combustion one you changed the -1560 but not any of the reactants?
Why do values from mean bond enthalpy calculations differ from those determined using Hess’s law?
IM SO THANKFUL FOR THESE VIDEOS
+skyeline ozer I'M SO THANKFUL THAT YOU LET ME KNOW. Seriously, thanks for the kind words.
9:40
So in this example, the value for the enthalpy of formation for H2 isn't given because you can't form H2 from it's constituents elements? Which is why you'd just take the value for the enthalpy of formation for ethyne only?
so for the intermediates, do you always automatically use the ones with the highest coefficients?
Thank you for the video - really helpful in covid-19 lockdown!
The direction of arrows at 13:30 onwards is hell of confusing. Why is the value of Ethyne taken as negative? Very confusing.
Thank you so much!!! This is extremely helpful! I really appreciate your efforts❤️
A much easier way to think about this without even having to draw out the thermochemical cycles is to just use:
(Enthalpy of) Combustion = Reactants - Products (CRaP, Combustion is Reactants - Products)
(Enthalpy of) Formation= Products - Reactants
:)))
I'm confused 11.21 about arrow so 2C+3H2 make the reactant and the products
How come H2 is considered in enthalpy change of combustion but not in enthalpy change of formation?
Thank you so so much these videos have been really helpful! I was wondering if you would be able to do a video on mean bond dissociation enthalpies as I struggle with calculating them. Thanks! :)
mariobros920 Thanks very much! I have a video already I believe... Try this one: ruclips.net/video/Ks1CtqsafSg/видео.html
Let me know if there's anything else I can help with!
(at 21:02) but if you leave it as 2H20 + O2 --> 2H2O and you dont have to multiple it by 2 to make a total of 3H2O... why would this be wrong?
near the end of the video, why did you add (-228)+(-85)? i thought it was reactants minus products since its an exothermic reaction?
+Blueberry 2 Love That's not how it works. I would always recommend using the cycle as it avoids any errors like those!
In the exam if you use the formula products-reactants or vice versa getting the same answer as you would if you used the thermocycle method would you still get all the marks?
As I find the thermocycles method really confusing.
moneyhoneyhoney Yeah, you get the marks. For me, I use the cycle because I understand the process more, but the marks are normally for the answer!
Wouldn't it be better to say that the definition of standard enthalpy of combustion as "ΔH of a substance..." rather than "ΔH of a compound"? Because you went on to use the standard enthalpy of combustion of hydrogen in your example, which is just an element. It was a little confusing ;;
(Also, nice Pokemon wallpaper at 8:20 , I didn't know chemistry teachers could be cool xD)
ye it's substance not compound
It says substance in the mark scheme, not compound. So yeah you're correct.
sir could you possibly do a vid constructing hess cycles using unknowns so you are given various reactions and you construct a hess cycle from the reactions given there's nothing on youtube going through it and i cant do it please help
hey youtube.... i always get the right value but it just has the wrong sign infront of it... im talking about combustion of x given the formation value of y... or vice versa
I think you've made an error sir because isn't enthalpy of combustion is the enthalpy change when one mole of compound is burned in OXYGEN. The calculation for the enthalpy change of combustion was not rea ting with oxygen
This video has helped me so much, thank you! I was wondering if u do any organic chemistry videos?
He has, they can be found on his channel :). Unit 2 playlist mainly for as
Jaz Miah thank you :)
How do you know if it's a double bond
its a triple tho. one carbon have 4 electrons in outer shell. it makes a triple covalent bond with another carbon atom and a single covalent bond with oxygen to complete its octet.
do we need to watch the other parts to fully understand hess law?
+Mohamed Maxamed Nope.
This is fantastic thanks very much!
If we were doing this in the exam, would we need to write the stuff in the boxes to get all the marks?
Sjaami Normally, no. The marks are for the answer - don't think I've seen one where marks are for cycle itself.
This man is a god, thank you
What's the difference between enthalpy of reaction formation and combustion, also why can you sometimes use enthalpy of formation to calculation enthalpy of combustion?
would it be possible if you could explain it the other method whereby you have the arrows following one direction e.g: C+O2=CO2 and then the arrows at the bottom not following the formation or combustion rules?
Racing Knight I'm a bit confused as to what you are asking... Can you try again, please?!
Sorry difficult to word it but basically there is another method i learnt whereby you don't do the combustion or formation arrows but the arrows point from left to right
Racing Knight OK, I think I might know... You can use another method where it is combustion = reactants - products and formation = products - reactants.
Do you mean that?
Thank you very much for the video! its really useful!
Awesome wallpaper, nd thanks for help
This is much better than a text book and 8:19 cool Pokemon scientist
Haha! Hadn't even realised that I'd done that!! But thanks for the comments!
could anyone help me and tell me how he got 228 and -85???? are they given in the exam question or do we have to solve it
they are given in the exam
With the thermochemical cycle at the end do you need to add oxygen to the reactants and products to make the reaction balance or does that not matter ?
Ryan Bower There's no need to add any oxygen into the cycle itself, no!
you know how you said in the enthalpy of formation that the hydrogen is in its standard elemental form, why is it that in the combustion it isn't.?
PLEASEEEEE HELPPPPP when constructing the combustion cycle why does it not matter that oxygen is also part of the reaction? By the oxygen being there doesn't it change the initial reactant e.g instead of A + B ---) C + D we now have A + B + 02 ---) C + D?????
No, because the Oxygen is used up in combustion.