Spectrophotometry and Beer's Law

We've learned about kinetics already, but how do we gather kinetic data? One clever method is by analyzing how the color of a solution changes over time, which is an indication of the concentration of certain compounds that interact with light in a specific way. This technique is called spectrophotometry, and this type of analysis will involve calculations using Beer's Law. Let's take a closer look!
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[@TasTheWatcher]

Beer's law?
Aye, I'll drink to that.

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*Beer Lambert Law*

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Me too

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[@rauter828]

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[@CoastalBachelor2009]

I'm Scott Beer and I approve this message.

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Hi Scoot Beer. My name is not Scott Beer.

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You're not professor Dave...

[@ProfessorDaveExplains]

Um, yes, I am Professor Dave. The channel is called Professor Dave Explains. See?

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It's because of the short hair isn't it😂😂

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[@abhisheksaha6035]

​@@ProfessorDaveExplainsUmm, that made us more sceptical 🤔

[@dumitru-claudiusergentu6720]

Hi Dave, since A is log (I/I0) and A is e*b*c, then I = I0 * 10^(-ebc), not I0*exp(-ebc) because it is not a natural logarithm but a base 10 logarithm.

[@OFFICIALGAMELORD]

I can't explain how to thank you .Tomorrow is my test and now I'm feeling relax.

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I love being able to understand something!

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lol

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Nice first like and Comment! Loving your channel Bro, I always learn something from you 👌🏻👍🏻😁😎

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Just shared the video with a friend who didn't understand wery well what they did just today at chemistry class😉

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chemistry is gay

[@jasonc0065]

And litnus is full of Cullors. Acid Lives Matter.

[@namithacd5650]

Can you do one for thin layer chromatography? Would be greatly helpful!

[@williamadams137]

Is “log” log base ten? Because i usually see people use “Log” or “ln” for natural log.

[@ProfessorDaveExplains]

yep if the base is not specified it's implied to be 10

[@yunus-ff2mw]

@@ProfessorDaveExplains Also, in our experiments, we took the logarithmic as 10 instead of e.

[@TommyZommy]

Dave, are you considering making computer science lectures?

[@ProfessorDaveExplains]

yes definitely one day!

[@samhagan1520]

You are easily better than my chem lab ta. Thank you.
Ps. I like the new haircut.

[@sammyapsel1443]

Can someone point out the following:
If Transmittance is defined as I/I0, then why isn't Absorbance defined as A=1-T , but rather as A=-log(T)?

[@sammyapsel1443]

What does then 1-T signify? The percentage of light that doesn't get transmitted which is not the absorbance?

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Hi professor.
I always learn something from your channel.

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Thank you from Algeria 💚🇩🇿

[@ronanclark2129]

Hearing all these numbers made me anxi😢us about my homework so maybe I'll watch the rest another time

[@jerryhymytang8859]

Hi professor Dave, I realized that you convert the log with a base of 10 to a exponential with a base of e, shouldn't it be in the base of 10? or else a natural log should be used instead of log in the base of 10

[@muthegameonline]

I also thought the same

[@GameHero531]

It's unfortunate and rather annoying but some textbooks and professors use log to mean "log base e", while others use it to mean "log base 10". It makes sense to just call log base e "log" if you know where the logarithm operation originally came from, but it's confusing nonetheless

[@CMThota]

​@@GameHero531 so basically he meant log base e (ln) not log base 10?
(the terminology is a bit new so just clarifying :))

[@GameHero531]

@@CMThota correct

[@autonews1621]

thanks bro, so annoying

[@vicentesayson2990]

Do you think sir, it's a good idea to create a spectrophotometer using specific wavelength only? For water analysis?

[@ProfessorDaveExplains]

seems like an arbitrarily limitation to me

[@vicentesayson2990]

@@ProfessorDaveExplains can you explain further?
By the way sir, I conducted some experiment using pasco spectrometer, i see that at 650nm wavelength the water absorbance of a distilled water is 0 , that's why i'm thinking to use 650nm as a standard source of light to determine the impurity of water

[@Ajay-Maurya.]

@@vicentesayson2990 anything would do right? light absorved same?

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Wow I was just lectured about this in chem and now studying for the midterm in 2 days what’re the odds hell yes professor dave

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Please how did our I become 1?

[@leenabulaban8450]

did you get an answer?

[@KituPattnaik-m2s]

It's a reference to 100%... If we call 100% as 1 then other percentage are that fraction of 1 😊.

[@leenabulaban8450]

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can please someone do a remix of the intro. I am talking 24h version

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he is he has canonically saved over 200 people from trains, mugging and chemistry mishaps. This is his penance as professor Dave caused the 2011 Fukushima Nuclear Disaster

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Thank you so much for the explanation!

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Plotting in real time with a computer? That’s just code for “undergrads”.

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Thank you professor Dave I have got relevant notes

[@scott_meyer]

Beer's law? Drink it.

[@rebornmmmmuch]

Very well explanation. Now I get the idea what this is all about🙏🏻

[@LittleWaffle]

Thank you for this well-explained video !

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I'm August beer and i approve this video

[@sunflora27]

thanks professor dave! This helped reiterate what my online course just blew through rather quickly

[@konstantinrebrov675]

Can you teach us how to make beer from a chemist's perspective?

[@yolo_earth]

Thanks for your video, Professor Dave! one thing to mention, it might better to tell log used here is actually base with e, not 10. In context it explained greatly, but itself I got bit confused for secs.

[@doriankiss1]

When it says log, I guess that's the natural log, ln.

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PROF. DAVE LANG MALAKAS (in filipino-only prof.dave is strong)

[@cliffordwilliams9597]

I'm confused how did we go from log I/i0, to e to the power of
stuff?? Should it have been ln I/i0?????

[@12uullaass12]

I think he made a mistake he mistook log(I/i0) with ln(I/i0).
it should have been
I = i0* 10^-(epsilon*b*c)

[@pritykarmakar4937]

Thank you so much sir🙏

[@sivasankar3349]

how 0.35 came for molar absorptivity?

[@annabellloyd8848]

its no nice to have an actual explanation and not be told you should know this or you can read this later at home

[@gria8329]

On the example why is the initial intensity 1, where did that 1 came from??

[@jimpanse1638]

Why is the number of moles a concentration? Isnt the concentration moles/volume? How can i get the total number of moles in the cuvet?

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🤍☺️

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Sir can u pls give a lecture about calorimeter principles and its application..

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Awesome 👍

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Thank you

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I think it's awesome your a flat earther now. Thanks alot

[@ProfessorDaveExplains]

wut

[@jagrutipaneliya4548]

Could you give me a name of software where I can plot my graph in better way?

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It is tough 🙁

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Good

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i love you so much istg thank u 🥺 for ur content ❤️

[@scigrl2870]

Hello, thank you for your videos - I show them to my undergraduate chemistry classes on occasion. However, there is an error in this video - the opposite of log is 10^x not e^x

[@kamilewais-orozco9971]

e^x is a notation for 10 to a power

[@kamilewais-orozco9971]

John Cavanaugh it doesn’t, but it’s helped me sort it out in my head

[@krellemaster]

log(x) is ambiguous and can be used to represent both base e and base 10. It is exceedingly common to use it as base e in physics.

[@Ajay-Maurya.]

​@@kamilewais-orozco9971 e is a special constant appearing in nature

[@rosapizana8597]

My professor used the example as an activity for the class but she asked which compound the measurement belongs to and I have no idea how to determine that.

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Fuck you're good Prof Dave

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This would have been useful 3 months ago, when i was actually seeing this shit in college

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One of the best channels in the field

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Proffessor Dave, I love you.

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Anyone here to learn all of AP chem for the 2020 exam? ~We're all in this together~

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Verification of beer lambert law through colorimetric

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Thank you professor David for this video.

[@woomp2004]

I thank you from the bottom of my heart

[@ayeshariaz8380]

Is the value of incident light always taken as 1?

[@abuhureyraat-tijani6113]

2:50

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👍

[@joshmemarrynagdey1639]

Thanks a lot... you make the topic easy to understand.

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Hi professor
Could you do a video about asanning electron microscop plz

[@chrisyun4960]

nice cut

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This relate with physics or biology???

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What was it about bonding? It wasn’t explained

[@evelynvarsovia3380]

Very clear explanation. thanks prof Dave

[@thatrecord5313]

Hair?

[@eewls]

Thanks

[@daviskimani1890]

Hey professor can you explain on how to calculate percentage transmittance. please😊

[@setsu2221]

Absorbance = 2 - log_10(%T)
Example:
1 = 2-log_10(T)
T = 10%

[@Zach-xm5wc]

Anyone else have a broken Spec 20 for lab?

[@petranuth7112]

Beer Lambert's Law

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Thank you so much 💓 💗

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Thx 4 U'r effort ♥️

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sexy hair cut

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Thanks 🌸

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Please professor Dave, why do you use Iø as 1?

[@leenabulaban8450]

did you get an answer?

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Thanks..

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👍👍👍

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Thank u professor Dave💗

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thank you for this!

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Why cut your hair??

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Thanks a lot professor...

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easy understand. tq sir

[@Mt.Trashmore]

Literally perfect timing!

[@yayapuncio497]

the more of a substance the light travels through

[@yayapuncio497]

the more of it that will be absorbed

[@yayapuncio497]

the higher the concentration the more of the substance will be absorbed

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u saved my life, thank you

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THANK YOU!!!

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Good vedio ♥️