Acids and Bases: Buffer Calculation - Past Paper Exam Question Walkthrough｜AQA A Level Chemistry

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Ace your A Level Chemistry exams with this in-depth analysis of a past paper question. I break down the complexities and guide you through every step to ensure you understand and can replicate them in your revision and exams.
This video is intended to be an ultimate guide on how to answer any acids and bases buffer solution calculation question you may come across under the acids and bases topic. This question is from AQA A Level Chemistry paper 1 2017 and involves a buffer calculation, which can be solved using mole calculations, Ka and pH expressions, rearranging equations, and principles of buffer solution equilibrium. This 6-mark question focuses on adding a strong base (alkali) to a solution of a weak acid and its salt. Keep in mind that if you add a solid base, you will need to follow a different method to this.
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Alternative buffer calculation question where acid is added: • Acids and Bases: Buffe...
📝 Access the resources:
Question paper: filestore.aqa....
Mark scheme: filestore.aqa....
Examiners report: filestore.aqa....
📚 Although this tutorial focuses on AQA, the concepts covered here are also applicable to other exam boards, such as OCR and Edexcel.
#alevelchemistry #acidsandbases #buffersolution #chemistryrevision #chemistryexam

[@easymodeexams33]

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[@anotherdayofpreventingtrav8513]

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[@easymodeexams33]

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[@easymodeexams33]

Nice!

[@elestrello6564]

chat are we cooked for paper 1 tmr

[@Alandd71]

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[@easymodeexams33]

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[@Gurpandslurp]

I got 8 hours to lock in

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@@Gurpandslurpeasy bro just cover acid and bases and thermodynamics. usually they are a huge chunk of marks thats what im doing rn

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@@Gurpandslurpi’m cooked

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[@lyssiesworldd8453]

Literally carrying me through my A-Levels 🎉 Please make some on Organic chemistry

[@easymodeexams33]

I've got quite a few organic videos on my channel already on organic synthesis, alkenes, NMR, benzene, and various mechanisms, etc., hopefully they're helpful. More to come!

[@user-su6js9po4l]

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[@easymodeexams33]

😂 thanks

[@rayzino3338]

🔥

[@moa7651]

super helpful!

[@angellll7272]

Thank you soo much! The way you explained the theory behind it, has really helped me to understand these calculations a lot better :)

[@easymodeexams33]

awesome! good luck

[@zarakhan6903]

legendddd! thank you so much. i recommended this video to all of my friends

[@easymodeexams33]

thanks :) good luck Zara

[@easymodeexams33]

I want to make it clear that this method applies to all buffer calculations that involve adding a small amount of acid or alkali solution (which is most cases). The method is slightly different when you're adding a solid base (e.g., NaOH) to partially neutralise the weak acid. If I get some time I can make a exam question walkthrough on this too.

[@parisasafdari13]

Please make this video🙏🏼, i was just about to ask why on an exam question they hadn’t added the moles of the base, and only subtracted one part. ( for ref paper 1 2022 question 4.5)

[@easymodeexams33]

@@parisasafdari13 I will add this to my list and get to it if possible 😄

[@lilac_turnip4767]

@@parisasafdari13what was the answer x

[@easymodeexams33]

@@parisasafdari13 Sorry Parisa but I haven't had time at all to make this video. Please check out page 5-7 of this pdf from chemrevise, it should help you out :) chemrevise.files.wordpress.com/2022/01/1.12-revision-guide-acid-base-equilibria-aqa.pdf

[@parisasafdari13]

@@easymodeexams33 thank you

[@iknowimwrongbut4491]

yess, needed this. Thank u so much your vids are great

[@easymodeexams33]

Appreciate the kind words and support :)

[@rutheshete2400]

u are a star, I was so confused; I got some hint now ,Thanks

[@easymodeexams33]

no worries :)

[@hbanksy]

Thanks for this mate, this one thing was just not getting into my head for the longest time

[@easymodeexams33]

no worries, good luck!

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UR A LEGEND OMDS THIS SAVED ME

[@MK-sh7ol]

naa cuz why can't our school teachers be this good :( My Chemistry teacher just chucked a bunch of equations at us and that's about it, so damn frustrating. literally every class he teachers has complained about him but unfortunately nothing has been done!

[@easymodeexams33]

I've had teachers like this too, long and frustrating

[@alexbesimming5835]

Would we be able to have a video regarding amines and amides, AQA If possible. Tysm for this vid 💓

[@easymodeexams33]

Yeah bro I got u, I remember your channel name and don't worry, your amine video request is still on my list, working through the list still but it's kinda long lol. expect an amine vid soon :)

[@easymodeexams33]

lol I just checked the list and got your amino acid request mixed up with amines. Which would you prefer first?

[@LennyGGnoRE]

bro where was this when i needed it a week ago

[@easymodeexams33]

lol

[@lilac_turnip4767]

Why is the moles being used in the final equations instead of the concentrations? Aren’t we meant to use concentration because of the square brackets in the KA formula? Thanks x

[@muchayevamadzimure8895]

you can use either moles or concentration im pretty sure based off the question. if you use concentration you will still get the same pH as with moles - it just depends on what the question gives you

[@LilMiro]

If you write it out, the concentrations cancel out since they’re on the top and bottom of the division

[@pinkiepiek1d808]

Your vids r the best thank u so so much😊

[@muhammadanas7791]

The pH value is a long ass answer indeed

[@easymodeexams33]

lol

[@Fatma-zahra212]

When you add naoh the ph must increase but due to the buffer it will resist the change so shouldnt the ph dectease and become more acidic.. my ph decreased from 4.43 to 4.35

[@gaanavmanyam9214]

If this question was with diprotic base, would you times concentration by X2 ? Then use the moles of OH to workout out the new number of moles fo HA and A- .

[@easymodeexams33]

That is beyond the A-level spec mate, so don't worry about it :) If you're genuinely interested and really want to know, here's a video from another channel explaining it: kzbin.info/www/bejne/q5jCdnyKodutm6s&ab_channel=JacobStewart

[@gaanavmanyam9214]

@@easymodeexams33 Oh ok, thanks for the clarification.

[@MasokaLeandre]

thanks boss

[@ravjayakodi2746]

@ 14:00 do you still have to show the cancelling out of the volumes ?

[@aishahsharjil7310]

please make for amine and amides

[@easymodeexams33]

fosho, got the amine topic as requested video already, so expect vid on it soon :)

[@alexreeves4503]

Thankyou!!

[@easymodeexams33]

no worries :) good luck

[@itsyogirlsavanna6640]

12:01 if you had HCL dissociating, would the H+ value be added to the ch3coo- valvue

[@AdamQ22]

If you still need it, no it would be added to ch3cooh and will be decreased from ch3coo