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1. Hi all,

Any chance anyone could walk me through this question? The mark scheme isn't being very useful and it's driving me insane! Thanks!

Markscheme here (Q (3)(c)(ii)): http://www.ocr.org.uk/Images/135166-...ments-june.pdf
2. (Original post by TauMuon)
Hi all,

Any chance anyone could walk me through this question? The mark scheme isn't being very useful and it's driving me insane! Thanks!

Markscheme here (Q (3)(c)(ii)): http://www.ocr.org.uk/Images/135166-...ments-june.pdf
Look, I could tell you how to do this, but you will have the same problem in the future. The best thing to do is to work through this interactive on buffers. It will gove you all of the tools you need to solve your own problems.
3. (Original post by TauMuon)
Hi all,

Any chance anyone could walk me through this question? The mark scheme isn't being very useful and it's driving me insane! Thanks!

Markscheme here (Q (3)(c)(ii)): http://www.ocr.org.uk/Images/135166-...ments-june.pdf
Right, so you gave me a neg for trying to help you!

That's gratitude ...
4. The presentation was actually useful, i'd reccomend reading through it. The last slides in particular explain this question well.

What is required for an acidic buffer solution?
Well, you need a salt, to generate the conjugate base. And of course you need an acid.

So, how do you form a salt? You can react the acid with something like NaOH to form a salt of that acid.

But if you have the same concentrations of acid and NaOH, the reaction will use up all the acid and you'll just have a salt, not acid. Remember an acidic buffer system requires both a salt and acid.

So therefore the acid needs to be in excess, so that at the end of the reaction you have acid remaining AND the salt.

So in this question, you'd get a mark for actually writing out what the salt is and then saying that the acid is in excess.
5. Can anyone help me with the whole of the chapter 3 , maths isn't my strong point at all. When I look at the past papers I feel clueless

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