AQA A-Level Chemistry - Equilibrium Constant, Kc

This video looks at the equilibrium constant, Kc.
Here are the notes from the video:
drive.google.com/file/d/0B099ziyBlLO_LVctbEQzX0pmSVU/view?usp=sharing

[@nuharahman6077]

7 years later and it is still great help! thank you!

[@Exists270]

its literally timless

[@paigebrown4727]

Thank you so much honestly you're saving my chemistry A-level. You've inspired me so much to even start my own channel on biology A-level for AQA.

[@AzraKahraman]

just subscribed

[@FerventRebutter]

Excellent lesson. Studying chemistry for one year on an Access course, and once again Mr Rintoul's channel has been outstanding. I hope I can find use in this channel once I'm at Uni! Thanks again!

[@ryanagar1114]

I'm on access too :D

[@FerventRebutter]

Awesome man, I finished mine last September and I'm currently studying at De Montort Uni - best of luck pal, hope you get to where you want to go :)

[@ryanagar1114]

Joshua Macleod what did you end up studying? I'm worried we haven't covered enough content for uni (doing biochem)

[@FerventRebutter]

I'm studying biomedical science, really similar to biochemistry. I know the modules can be different, so I'll break down what I covered on Access: - Physics (pass/fail) and Advanced Physics (graded) - Environmental Science (graded, I think?) and Ecology (graded) - Foundation chemistry (graded) and redox, equilibria and energetics (graded) - Loads of graded biology content, but cannot for the life of me remember the unit names haha. - Maths (ungraded) and study skills (ungraded) If you've covered anything around these, I'm sure they'll be of ample information. It also depends on what you're issue is concerning; the likelihood of being accepted or how you'll find the content; - De Montfort accepted me with just passes; though I got 45/45 distinctions (I had low expectations :P) - they even offered me a £1000 scholarship for enrolling with an Access qualification. So universities are keen on giving you a chance :) - In regards to what foundational knowledge you will need is anyones guess, but you will often find the universities will go right back to basics to ensure you're ready to grasp the better stuff. (We were literally taught that the mitochondria was the power house of the cell). Don't fret too hard, and remember that there will be handfuls of other people with Btecs, Access and other non-A-level qualifications in the same boat as you. If you're worried about whether you are capable, please take heed - I left A-levels with E's in everything (that I didn't get U's in) and have managed to attain Firsts in EVERYTHING thus far at Uni. I hope you do really well, and please ask any more questions. :)

[@ryanagar1114]

Joshua Macleod thanks man, motivating words. I'm heading towards my last exams and ontrack for 45/45. I'll have to look into the scholarship at Nottingham. How did you go about getting that? was it the same route as scholarships for AAA students. My plan is to read over A2 topics and bring up my maths over summer.

[@user-yf6ki8ce5t]

When chemistry gets too much............. 7:29

[@jemmachoudhury9452]

Is it possible that you would ever consider doing AQA A Level Biology videos? Love your videos by the way, great help!

[@__III__]

@Emerson Lennox shush u bot

[@raza78695]

I think chemistry is his specialty that's why he hasn't made any

[@ojassomethin]

@@raza78695 Yeah duh

[@danzyt2621]

Innit stfu biology is for obese people

[@kalashnikid47]

My G 8) Thanks for the great video, hope to do well on my mocks :D

[@MrERintoul]

+MAR Fingers crossed!

[@mali-hz4cb]

Great video! Glad your still doing videos for old spec A2! Thanks! Btw how many videos do have left to do for unit 5 or is that completed?

[@MrERintoul]

+mali 45671 There's a few more yet.

[@dennisgjoka10]

Thank you so much, your videos are extremely helpful! No wonder you barely get dislikes

[@sherrypahilanga2172]

hi, if anyone can reply..why did you get methanol as 0.07mol when it states that 0.17mol was found in equilibrium mixture.. i want to know why he had to do 0.24-0.17 process... and also i want to know what is 0.24mol, 0.17mol, 0.07 mol separately to clarify my doubt... :(

[@andrejameske7556]

omg this is exactly what i dont understand omd

[@danielbrody382]

Same, I can't see where that is coming from. It would be more helpful if he explained his workings

[@Lalz1997]

The "Nooooo effect" got me 😂😂👌🏽

[@MrERintoul]

+Lalz Boo Haha!

[@samimuhammad1201]

You are the best chemistry teacher

[@johnholme138]

Flawless video mate, cheers

[@benchesters1052]

could you do a video designated to A2 AQA Equilibrium Constant, Kp with exam questions included? that would be really awesome

[@peaceplace4565]

It would be helpful if u tells us why you’re dividing, subtracting, etc when you’re doing the questions.

[@arvingasco7606]

At 8:50 the units are mol dm^-3 all over 1 which is still just mol dm^-3

[@salma-4930]

Just wanted to notify you that the Redox/Equilibria videos aren't in the phyisical playlists!

[@ayesha1929]

off-topic but your voice is so soothing... btw very helpful videos!

[@uas4613]

BRILLIANT!!!

[@georgiahalliday2278]

this is amazing thank you !!

[@MrERintoul]

+Georgia Halliday No worries!

[@hppsgm]

Oh, just did my CHEM 4 mock 2 hours ago, nevermind at least I can be more prepared for the real exam now thanks to this xD

[@MrERintoul]

+hppsgm Have you completely finished CHEM4?! Or do you do all of CHEM4 and then start CHEM5?

[@hppsgm]

+E Rintoul We have done learning all of CHEM 4 and start learning CHEM 5 after the half term in January. We started CHEM 4 straight after are AS exams were over last year so that's why we've finished now.

[@MrERintoul]

hppsgm I seeeee. So you've not done any CHEM5 at this point?

[@hppsgm]

+E Rintoul No, we haven't done any CHEM5 at this point, so no doubt your videos will really help a lot. Are teachers described CHEM5 as "it either makes you or breaks you" so this is going to be interesting....

[@MrERintoul]

hppsgm Haha! Yeah, CHEM5 can be a bit of a killer BUT if you can do well on it, it's a really great chance to get loads of UMS as the grade boundaries are normally quite low!

[@catherineaalders920]

Thank you for your new videos :)

[@MrERintoul]

+Catherine Aalders No problem at all :)

[@donnylass92l39]

this was really helpful thank you!

[@MrERintoul]

+Rhiannon Maxey I'm glad!

[@GN8954]

If we're studying the new spec should we watch it with this 'new' equilibrium video or watch it with your old one??

[@moelforjani2922]

And he's back!!!

[@MrERintoul]

+mohamed Ibrahim Oh I never left, Mohamed.

[@hamaadsiddiqui5480]

@@MrERintoul but now you did :(

[@gasIighter]

8:25 so if the number at the bottom is bigger the units is mol-1dm3?

[@xBeeeefy]

Skip to 9:00 to learn how to answer the actual questions

[@epicspartan10]

zeyn not all heroes wear capes

[@hi44098]

Archie Goodman hahahah

[@azaankhan5334]

@@epicspartan10 lol🤣

[@rifatchowdhury7384]

Man I wish you were my chemistry teacher

[@jackdevin387]

What software do you use to make your notes on? :)

[@mrqwerty4792]

[@ohshitwaddup6299]

YAASSS MY G RINTOUL

[@lisaschneider9151]

Do you have a link for the website you mentioned? - Can't find it. ._.

[@WaseemAli-jw8bh]

PLEASE GO THROUGH MORE PAST PAPER QUESTIONS!!

[@skrrelmi7563]

where did 0.07 come from, the question said 0.170.? can you please do a video on using the quadratic equation to find Kc when Kc is X

[@jcorky91]

Skrr Elmi for anyone wondering years later, 0.24 - 0.17 = 0.07

[@carefull8365]

Hahaha lol finally understood it tnx

[@sagharusman3815]

@@jcorky91 I wondered lol, Thanks!

[@sherrypahilanga2172]

@@jcorky91 but why did he have to minus. isnt 0.17mol already the mole in equilibrium mixture of CO? am i misinterpreting something wrong? pls help

[@DogeDogeriffic]

@@sherrypahilanga2172 a year late but screw it. I’m no expert (which is why I watched this video) but I’d assume 0.240 was the initial mol number and 0.170 is the mol after equilibrium was reached. Therefore the mol difference is just before and after so 0.240 - 0.170

[@caitlin4938]

Don't suppose there is a pH of weak acids calculations/ pH calculations involving neutralising video(s) coming soon? Happy New Year! Ps. Your videos are saving my grades right now!! Thank you! :)

[@MrERintoul]

+Caitlin I don't know if I've done a weak acids one yet. I thought I had? If not, it'll be done in the future.

[@rachel5266]

Will you be uploading more videos for A2? :D

[@-lucifer9328]

Funny how the practise question that we learnt on the video came in one of my class tests and now I’m watching the video after the test, as Gordon Ramsay would say “FUCK ME!!!!!”

[@abcdefghijk___opqrstuvwxyz147]

13:17 I don’t understand where 0.070 mol came from, wasn’t it 0.170 mol of CO?

[@kemuelfavour9292]

So helpful

[@solomonneild4014]

i am doing something to do with quadratic formulas in our chemical equilibria topic, could you explain what its used for please? Love the videos by the way, recommended them to all my friends

[@MrERintoul]

+Solomon Neild No idea. If you can send me an example I may be able to help!

[@GeeGeeGweppo]

was getting confused at 13:21 but then noticed i did it right. (You said 0.07) but in reality its 0.17 therefore it would be a 1:2 ratio x2 = 0.34 0.38 - 0.34 = 0.04 for H and 0.17 for Methanol? Correct?

[@samhansen794]

No, I think he's correct

[@alexanderazzopardi5681]

yh i got 0.04

[@SentilSpark]

LOL SAME profile pic

[@yoiki2897]

Can you apply the ICE box method to the first question?

[@abbabbcbbcbb]

5 Years later but yeah what he did was an ICE table he just didn't draw the box

[@jake.simp11]

Its great that you're still covering the old spec Sir. Also, i have uni offers from york and manchester to study chemisty, which should i make my first choice?

[@MrERintoul]

+SorleyBoy98 Excellent, well done! That all depends on the offers! The highest offer should go above the other otherwise you stand a chance of not getting a place if you miss you top choice. But, if they are both the same offer, it depends on which uni you like best! I love Manchester as a place and York is lovely too, if a little quieter.

[@jake.simp11]

+E Rintoul Thanks for the advice, great vid as always!

[@felicityk4867]

Aromatic chemistry, next please please please!

[@MrERintoul]

+Felicity K Maybe...

[@Zen_Zen_Zense]

@@MrERintoul 😂😂😂

[@rafhi97slem]

Could you do more questions about kc and group 7 element?

[@MrERintoul]

+rafhi97slem Probably not. I would say that you need to do those independently to become more confident!

[@miyakakinshasa25]

THANKS A LOT!!!!!!!

[@frankding7584]

Thank you so much! Also, does anyone else think that the title gives MCR vibes?

[@sophiea2697]

At 14:24 Q3a where has the hydrogen concentration gone from the methanol concentration (0.14)? Because it's says 0.07. Do you not add the change in concentration for both reactants to get the concentration of the product? (0.21) . I'm confused.

[@ES-no3wg]

you were great more videos please

[@MrERintoul]

+Violla Rama No, YOU were great. There will be more...

[@zannatul23]

how can i explain something in terms of Kc, Ik that pressure and concentration doesn't change the value of Kc??

[@MrERintoul]

+zannatul Zan I'm not sure I understand the question?

[@ahmodulkabir6761]

I really appreciate your videos as they are really helpful. I've had to learn most of the unit 4 content on my own. The teacher that got appointed in September didn't have a proper grasp of the A-Level content and didn't 'teach'. The management have only recently just got rid of her. I'm a bit worried as I feel as though we're behind with things as we haven't even touched Unit 5.Thankfully, having looked at your videos and doing past papers questions has reassured me. Anyways, I was wondering if you'd do any EMPA practice papers?

[@MrERintoul]

+Ahmodul Kabir Having looked at a few comments recently, there are a lot of schools that work through CHEM4 first and then move onto CHEM5. We do it differently where I'm at and as such, I have almost finished CHEM 5 with one class and with the other, we are a good way through CHEM4. I would say that by this point you probably want to be about done with CHEM4 so that you have plenty of time for CHEM5. However, you can go quite quickly through CHEM5 if you work hard at it!

[@adonis1up]

God bless you Mr Rintoul

[@MrERintoul]

+Rashid Yousif Cheers, Rashid!

[@connorkirk7400]

Got it 👌🏻

[@Amy-le6jp]

Brilliant video! Thankyou!!

[@a.Bader97]

Sir, at minute 10:00 you say their is 1.5 moles of B. My question is why didn't you put 1.5 as your coefficient in regards to the B. Because then you wouldn't have 0.4 moles of B (like you did with A) but rather you would have 0.8 as it is now a 1:2 ratio rather than a 1:3 ratio. Can you please clarify this, thank you.

[@MrERintoul]

+"So where are you going?" (chapter 81 verse 26) I'm not sure that you're really understanding what is going on here... The numbers that I wrote down are nothing to do with the ratio, they area the actual values of those reactants and products before and at equilibrium. The ratio can NEVER be 1:2 as the numbers in the equation do not allow this. The ratio of A:C and of B:C is 1:3. ALWAYS. You mention having 0.4 moles of B. That isn't the case, rather, from the amount of C at equilibrium and from the ratio of B to C, we know that 0.4 moles of B must have REACTED, leaving 1.10 moles (1.50 - 0.400). Does that make any more sense now? If not, let me know how I can help further.

[@a.Bader97]

E Rintoul fantastic, you've cleared it up! Thank you so much as always. By the way, how many more videos until you've completed unit 4? Thanks again!

[@MrERintoul]

+"So where are you going?" (chapter 81 verse 26) Oooooh. Not many I don't think. Maybe 4ish?

[@a.Bader97]

E Rintoul "watch out this space!" :)

[@georgeashby4852]

brilliant

[@rdunteas1587]

Thanks for the vids, when you say temperature is the only condition effecting kc why doesn't pressure effect it? as surely the equilibrium will shift depending on number of moles therefore changeingthe amounts of reactants and products

[@ENZOxDV9]

found out yet I'm a bit confused on that too

[@rdunteas1587]

+ENZOxDV9 unfortunately not!

[@ENZOxDV9]

Sebastian Owen i think it's because the equilibrium constant is only a measure of concentration so although there are moles the constant won't change by it.dunno why temperature changes it

[@mujdafy]

Because pressure has the same effect as concentration, its the change of the amount of molecules in a given volume therefore would not have an effect on Kc because the pressure of the molecules on the opposite reaction would change too

[@ibrahimshafi2064]

At 14:00 it's 0.170, not 0.0700

[@Mo786productions]

Ibrahim Shafi yh exactly

[@fatimamarah8315]

life saver

[@bananapancakecat]

Its 0.07 and 0.24bc: The mole ratio is given in the equation: 1 mole of CO reacts with 2 moles of hydrogen t make 1 mole of methanol If you start off with 0.24 mol of CO and there are 0.17 mol at equilibrium then 0.24 - 0.17 mol of CO have reacted. From the stoichiometry of the equation this makes the same number of moles of methanol. From the stoichiometry of the equation twice of much hydrogen must have reacted. Subtract moles of hydrogen reacted from original moles present (given in the question) to get moles of hydrogen remaining. You now have the number of moles of each component.

[@lemonadepie9631]

YOU ARE SO HELPFUL I HAVE MY CHEM EXAM TOMORROW, BLESS YOU, CHILD

[@brokecoder]

Sir, Ples may you me reply me? @14:04 i don'nt understand why you subtracted 0.380 and 0.14. Isn't the question asking about how much hydrogen is used to come to an equibrium?

[@MrERintoul]

+MaleVip We know that 0.07 moles of carbon monoxide reacted in reaching equilibrium. Because the ratio of carbon monoxide to hydrogen is 1:2, that means that 0.14 moles of hydrogen must have reacted. Because there were initially 0.38 moles of hydrogen, the amount at equilibrium would be 0.38-0.14. Get it?

[@daryasalh4910]

E Rintoul but its 0.170 not 0.07

[@peaceplace4565]

@@daryasalh4910 no. 0.17 is for carbon monoxide. The question is asking about methanol which is why he subtracted the values.

[@fatimaawow3193]

I love your chemistry videos, could you post similar ones for Biology AQA?

[@MrERintoul]

+Fatima Awow I'm considering branching out into Biology but at this point I want to get the Chem videos to a point where I'm really happy with them.

[@prisila888]

+E Rintoul what about physics

[@MrERintoul]

M.D.L TM Hmm. I'll never say never! BUT, the last time I did Physics was when I was doing my A-Level back when I was at school!

[@cameronretason5073]

don't get where 0.07 came from wasn't it 0.17

[@maryel6266]

Cameron retason yeah

[@joana359]

I'm very late but you do 0.240-0.170 which gives you 0.07 moles that reacted.

[@razmatenachrazmaten5320]

@@joana359 do you know why before equilibrium, there are 2.5 moles in total of reactants and products but then at equilibrium (11:31) there are 2.9 moles in total? How does that make sense?

[@xenne.]

How did he get 0.07 for methanol

[@jacobsuresh3743]

Legend

[@tejpatel2659]

Just out of curiosity, what effect does increasing temperate have on Kc?

[@areebaa1595]

i will try and explain this: so, an increase in the concentration of products (or a decrease in the reactants) will cause Kc to increase. but a decrease in the concentration of products (or a increase in the reactants) will cause Kc to decrease. you should also note that you can find out if the products/reactants are being increased/decreased using Le Chateliers. hope this helped xx

[@ibrahimshafi2064]

@@areebaa1595 conc doesn't have an effect on Kc value... What you're saying is correct form equilibrium, howevever, temp does have an effect the Kc value but only temp

[@areebaa1595]

@@ibrahimshafi2064 i believe it is relative to each other but i will check my notes just to make sure :)

[@hafsahk1310]

Why does temperature affect the equilibrium constant Kc?

[@hafsahk1310]

aired

[@mzmz12345]

Why do you divide by the volume?

[@edwardharrison7373]

Excuse me sir, but the question at 12:00 is confusing me. If the hydrogen lost 0.14mols then surely the methanol will have gained those moles aswel as the moles lost from the carbon monoxide? totalling at 0.21 moles of ethanol?

[@kadekevin566]

same question here!

[@MrERintoul]

+Edward Harrison Nope. It may help to actually draw the structures of the substances in order to actually see what it going where...

[@macbookpro8014]

Could you please incorporate some exam questions into these videos? Thank you so much and these tutorials are very helpful!

[@jsbaasi]

look at the other half of the video you silly goon

[@moneyhoneyhoney9047]

How does the kc change with temp? does it increase as temperature does??

[@MrERintoul]

It all depends on the equilibrium and in which direction the reaction is exothermic/endothermic.

[@NiaKF]

Why did you square 0.275/1.50 and not the one next to it ?

[@markp3720]

+Nía Feisal As that is for the H2 and there is 2 moles of H2 in the equation so the concentration of H2 (in the equation for Kc) is squared. But the one next to it (which is the Concentration of CO) is not squared as there is only one mole of CO in the equation so the concentration of CO is to the power of 1 (so not squared). Hope this helps!!

[@NiaKF]

+Marco Polo I see, thank you

[@Glitterfm2133]

How do you calculate this with your brainnnnn?

[@MrERintoul]

+Glitterfm2133 Haha. I don't, I cheat and use a calculator but I don't put it in as there's no need for everyone to see it!

[@reiantaank3314]

Sir, it should be mol dm-3 for the first equilibrium constant, instead of 'mol-1 dm3'. 8:30ish.

[@aneeqster5]

+Reian Taank Did you watch the video without sound?

[@MrERintoul]

+Reian Taank I actually am watching it without sound so I don't know...

[@reiantaank3314]

+E Rintoul Nah, you were right.

[@Useless0305]

You're a fucking god, make this stuff so simple, thank you

[@anasmohamed7110]

14:22 I think you accidentally used 0.07 instead of 0.17 moles for carbon monoxide?

[@tomtom8057]

Fok i dont understand how do you get 0.4? From A+B equilibrium 3C?

[@Zara-el6yq]

Tom Tom 3 moles of C is 1.20, so 1 mole would be 1.2 / 3 = 0.4 moles

[@bazi5646]

Hopefully my Paper 1 exam goes well today...!

[@maryel6266]

Bazi Reloaded same

[@Psyxiiko]

@@maryel6266 how did you do?

[@klausaceline7027]

hi sir can i ask where do you get 0.070?

[@abdullahsaim5593]

I guess that is a typo cause it was supposed to be 0.170

[@yujirohanma203]

@@abdullahsaim5593 no it is meant to be 0.070 as that's how much methanol is produced

[@yask7982]

you failied to mention about what would happen when there's two or more mol/ dm3 on the top or on the bottom on 8:50

[@yask7982]

Failed*

[@MrERintoul]

+Yas K Correct.

[@moneyhoneyhoney9047]

please explain?

[@ConquerMirage]

why is dm^-3 X dm^-3 -6? Why is it not -9 ( 3 X 3 = 9)

[@cosminlive199]

Rules of indices. When you multiply two numbers you ADD the powers. so dm^-3 x dm^-3 = dm^-6 as -3+-3 = -6

[@ConquerMirage]

Thanks

[@mujdafy]

I love you lol :(

[@barbodoskoueian5959]

mate shouldnt it be mol2 dm9?

[@muadhzahoor6421]

yes i think it should

[@muadhzahoor6421]

@rohan ahh yes thanks for that, that rule completely slipped my mind

[@Jessica-xw1rb]

this topic (the calculations specifically) is making me so stressed out and angry

[@kumaxtalk]

Can you write bigger please, there's just so much space.

[@jahnavi1298]

stop with the adverts every two seconds istg

[@gankingmaster1557]

Shits still useful bro cheers

[@Geassmaster55]

More past paper questions on these please

[@trigobrooken6260]

SIr what writing program are you using

[@abirulislam664]

-3 x -3 = 9 not 6 btw

[@MrERintoul]

Abirul Islam when you multiply things with indices, the indices are added.

[@maryel6266]

I have my chem exam today and I haven't even revised anything

[@jaylakayalah5798]

Ugh same

[@TGAMGaming]

MathsManOnPcIn1080p

[@xBeeeefy]

Man took 6 mins to just write equation down

[@samiraahej2743]

Thank you :((❤️

[@securitybreach5182]

im cooked

[@london.blooger]

Bad Accent 👎🏻👎🏻👎🏻