OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

has anyone got any good nmr resources

Your first answer looks right to me.

Henderson-Hasselbalch equation:

pH = pKa + log(A-/HA)

3 = 4 + log(A-/HA)

log(A-/HA) = -1

So the ratio must be 1/10 as 10^-1 = 1/10

Your second answer would be the opposite so 10/1 as you need log(A-/HA) = 1.

I think anyway, I could be missing something.


Posted from TSR Mobile

Here

Hi
Can you please explain how you have done this question. I really don't understand it. Thanks

Posted from TSR Mobile

Could anyone explain 3??
I thought the weakest oxidising agent would be the strongest reducing agent and be the one with the most positive electrode potential?

the weakest oxidising agent would be the strongest reducing agent and be the one with the most negative electrode potential

The negative sign tells you the half equation doesn't want to go from left to right as written

Anyone know how to work out the final species?

V²⁺

Okay just did Jan f325 and got 80! However, the last question and the electrode potentials were confusing. Can someone help me understand how to answer question 7d. Here is a link:
http://www.ocr.org.uk/Images/144762-question-paper-unit-f325-01-equilibria-energetics-and-elements.pdf

where can i find hard NMR questions? or if i can find any stretch and challenge chemistry questions in general?

When drawing optical isomers, does it matter you order the groups around the chiral centre???