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OCR B (Salters) F332 Tuesday 4th June 2013 Exam Discussion (Now Closed)

Reply 1040

super121

5

Original post by MintCrepz

How on earth were we meant to know this at AS?

Original post by krisshP

It does not say in the spec that we need to know the systematic nAvq,e of NO2- ion, yet they asked that. Isn't that illegal?

I agree with you, I only know because i've done F334 and F335

Reply 1041

tipani

I i have to admit, i didn't this exam easy at all, but from past experience, there wasn't any particularly hard questions apart from the question at the end which was quite querky.

I reckon atleast 83 for the A, and may be up to 85. Remember they usually have to cap the percentage of people who achieve A's and i know a lot of people who seem like they got close to 100, or atleast 95.

Reply 1042

anthonyrf

Original post by anthonyrf

What did people say for the bonding question!? I said hydrogen bonds between molecules of propan-1ol and pentene had Id-Id and so on..

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Anyone? lol

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Reply 1043

tigerz

Original post by anthonyrf

Exactly what I said!! lol

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Original post by MintCrepz

Yeah yeah

sounds like we got similar answers !

Haha yup, seems like i've gotten similar to quite a few people on here! :wink:

Original post by juniorx

i said less co2 and the total enery was lower?

Yeah thats probably gonna be alright, defo the co2 bit

In fact for the C-F bond its more strong as its a smaller atom right :P

I found the paper decent but a lot of my friends hated it haha, so I think boundaries will be about 65-70ish for an A?

(edited 10 years ago)

Reply 1044

juniorx

2

Original post by krisshP

It does not say in the spec that we need to know the systematic nAvq,e of NO2- ion, yet they asked that. Isn't that illegal?

this is ocr we're talking about...

(edited 10 years ago)

Reply 1045

Tejmasta

Original post by super121

Nitrate (III) is the systematic name

phew, thought i might have gone that wrong when people said it was nitrogen dioxide

Reply 1046

booooomblastruin

Original post by juniorx

i thought it was n2o

Wouldn't that would mean that the oxygen forms two single bonds with the nitrogen and then has two lone pairs left over? :s-smilie:

Reply 1047

super121

5

Original post by juniorx

i said less co2 and the total enery was lower?

I said that :smile:

Reply 1048

steviep14

10

For the C-F bond... I just said "higher frequency UV required as more energy is required to break the C-F bond as C-F has a greater polarity than C-Cl and so greater bond enthalpy"

Reply 1049

usycool1

19

Original post by krisshP

It does not say in the spec that we need to know the systematic nAvq,e of NO2- ion, yet they asked that. Isn't that illegal?

It could have easily been worked out using the oxidation states (which is on the spec).

Reply 1050

super121

5

Original post by Tejmasta

phew, thought i might have gone that wrong when people said it was nitrogen dioxide

Nitrogen dioxide? :O I'm pretty sure it was an ion and N2O not NO2

(edited 10 years ago)

Reply 1051

abzy1234

14

Original post by tigerz

Haha yup, when I did f331, someone sneakily copied it so its possible! Yeah that was standard though got 1.17 (3 sf) for the frequency and 7.something for the bit above!

We shall see! And ditto, got the same as well :biggrin:

Original post by MintCrepz

How on earth were we meant to know this at AS?

You worked out the oxidation state of nitrogen in that ion in the earlier part when it was talking about oxidation, and there's two oxygen atoms, so you know it's going to end in ate... Systematic means you need to put in the oxidation state of the central atom in brackets.

It's like the chlorate section in the AS revision guide :smile:

Reply 1052

juniorx

2

Original post by tigerz

Haha yup, seems like i've gotten similar to quite a few people on here! :wink:

Yeah thats probably gonna be alright, defo the co2 bit

In fact for the C-F bond its more strong as its a smaller atom right :P

i said the c-f bond length is shorter and that flourine is more electronegative so will form a stronger bond (electrons occupy a shell closer to the positive nucleus-distance is less)

(edited 10 years ago)

Reply 1053

krisshP

14

Original post by abzy1234

It really doesn't matter tbh. You learn this in F335 in a bit more detail; the A2 revision guide also writes Nitrate (III) ion:

If it's in F335 A2, why were we asked this question? It's not in the F332 spec, so it's an illegal question by evil OCR salters.

Reply 1054

anthonyrf

Original post by steviep14

For the C-F bond... I just said "higher frequency UV required as more energy is required to break the C-F bond as C-F has a greater polarity than C-Cl and so greater bond enthalpy"

Yeah that's correct.

I kinda said that the C-F bond was stronger than the C-Cl bonds as flourines bonds are closer to the nucleus or some crap like that :/

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Reply 1055

MintCrepz

5

Original post by abzy1234

We shall see! And ditto, got the same as well :biggrin:

You worked out the oxidation state of nitrogen in that ion in the earlier part when it was talking about oxidation, and there's two oxygen atoms, so you know it's going to end in ate... Systematic means you need to put in the oxidation state of the central atom in brackets.

It's like the chlorate section in the AS revision guide :smile:

Yeah yeah that's how I knew it was III but I thought only NO3 was nitrate nothing else, whoops.

Reply 1056

Tejmasta

Original post by booooomblastruin

Wouldn't that would mean that the oxygen forms two single bonds with the nitrogen and then has two lone pairs left over? :s-smilie:

no, nitrogen is the central atom so there is a triple bond between it and the other nitrogen and a dative bond with the oxygen (both electrons from nitrogen) giving it a linear shape

Reply 1057

steviep14

10

Original post by anthonyrf

Yeah that's correct.

I kinda said that the C-F bond was stronger than the C-Cl bonds as flourines bonds are closer to the nucleus or some crap like that :/

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