Ocr gateway CHEM 4 5 6 markscheme

The equation = volume of acid x concentration of acid = volume of alkali x concentration of alkali.

What I don't understand is where it says you have to use the 'end point'.

I understand what you mean but the volume of acid was continued beyond the end point?

the end point of a titration is the volume needed for it to fully neutralise, so it's the pretty-much vertical bit on a pH curve
not 100% but i think you use that value because when you actually do a titration you stop when the indicator changes colour and you've neutralised the solution and record that value

Yea I understand what you saying but checking previous mark schemes the good thing is you will get marks for just having the correct formula. As its probably 3marks for calculation and 3 marks for the other part of the question.

the end point of a titration is the volume needed for it to fully neutralise, so it's the pretty-much vertical bit on a pH curve
not 100% but i think you use that value because when you actually do a titration you stop when the indicator changes colour and you've neutralised the solution and record that value

Oh no! How many marks was it? I'm sure you'll definitely get 1 at least.

What I did was mass/mr = mols
0.16g/2 (H2 =1×2)
This got me 0.08 mols
1 mol = 24000cm^3
Divide 24000 by 12.5 bc 1/12.5 = 0.08

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It was 2 marks. Where did you get 12.5 from? I just did 24000/0.08...but I think I rearranged the equation incorrectly.
I thought you obtained your answer by doing 0.08 * 24000

steorotypical

It was 2 marks. Where did you get 12.5 from? I just did 24000/0.08...but I think I rearranged the equation incorrectly.
I thought you obtained your answer by doing 0.08 * 24000

Aren't you supposed to convert 24000cm3 into dm3 ???????

Aren't you supposed to convert 24000cm3 into dm3 ???????

No because this paper is worth more than the other paper

Paper 1 ums
A* = 126
Paper 2 ums
A* = 144
Coursework ums
A* = 90

To get an A* overall you need 360 ums points