OCR F324-June 2013 Chemistry

i got 48/60 which shouldve been an A but the grade boundaries were higher for an A for that paper so got 68 UMS what about you?

do you think i'll be ok?

Lol I got a D so you should be fine
I didnt revise at all for this paper because I planned everything really stupidly and wanted to get a high grade in biology so I didnt have to retake it ..... BAD IDEA.
But yeah, just work hard for the remaining weeks

haha well im also retaking aqa biol4 as well!! so im worse off than you how did you do in biol4 i also got a B

pi bonds are sited above and below the plane of the carbon atoms so 3

Hi could someone help me with these two OCR Chemistry F324 questions that i have:

Q1.) When HOCH2CHO reacts with tollens reagent HOCH2COOH is produced not HOOCCOOH. Why ? Is tollens reagent only strong enough to oxidise aldehyde to carboxylic acid not alcohol to carboxylic acid?

Q2.) Propan-1,2,3-triol and C17H31COOH react to produce triglyceride. Deduce the number of carbon double bonds in the molecule of the triglyceride.

Answer is 6. But how is this worked out?


Thanks

Guys am I right in saying that NaBH4 DOES NOT reduce carboxylic acids and esters and only reduces the aldehydes/ketones? If so why is that?

Can someone explain how you work out the number of different carbon or proton environments in a compound I seriously have no idea this is so frustrating D;

Pretty sure it just means Maths should be a subject you're taking lol so you just need an A or a B in it?

I don't think its something you need to know and its not on the specification or in the book so you shouldn't need to learn it. But from what I know carboxylic acids can be reduced. Not sure about esters, I don't think they can though.

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Carbon is simpler than proton, for carbon just count the number of carbons. It gets a little more tricky when there are equivalent carbons but just remember that they only show as 1 peak, for example Cl-CH2-CH(CH3)CH2CH3 would have 5 peaks but Cl-CH2-CH2-CH(CH3)2 would have 4 peaks as the last 2 methyl groups are equivalent (essentially they are bonded to the same thing)

Proton is a similar idea, just look at the hydrogen environment, all the hydrogen's in a CH3 are equivalent so they show up as one peak as they dont split each other.
If you have CH3-CH2 then the first methyl would be a triplet (n+1) rule and the second carbon would be a quartet.

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I got just an A in Biol 4 so now need a mid B in biol 5 to get an A. How r u finding biol 5?

If I used your example of Cl-CH2-CH(CH3)CH2CH3, where did the 5 environments come from? Does the methyl bonded to CH count as the same as the CH3 at the end? And there are 2 CH2s so are they different or the same? I got Carbon environments: C-Cl, -CH2-, CH... and then I'm lost LOL sorry I'm just so confused >_< I'm ok with the splitting patterns though I just hate identifying number of C/H environments -.-