OCR Chemistry B (Salters) Thursday 10th January Discussion

It will be moles to calculate enthalpy change

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Bra look in the cgp for your answer. Im correct.

what were the bond angles for A and B ? I put 120 for both, thinking they both had 3 areas of electron density - but did the one w/o the double bond have a lone pair and therefore 109?

Nope second one is 109 because theres also a hydrogen bond around the carbon atom, its skeletal so you cant see it on the diagram

Reply 181

Mangodepo11

8

Original post by krisshP

yeah, but isn't that a bit too picky?? :frown:

thanks anyway

Yes probably, but you wont get anything for active site. Ms answer will probably be.

-Coats surface -prevents adsorption

Reply 182

exams567

what about catalyst adsorbed on surface too stongly, prevents catalysis

Reply 183

krisshP

14

Original post by Richyp22

Yes probably, but you wont get anything for active site. Ms answer will probably be.

-Coats surface -prevents adsorption

thanks! good luck to you :smile:

I got my mock tommorow of F331 so I probably will be doing the same paper as you.

Reply 184

Isaacymoose

Original post by Richyp22

Neither will get the marks. look in the cgp, has to be difference between start and end mass of the fuel.

Yeah so you need to know the mass of the fuel.

Reply 185

Tikara

Original post by Richyp22

Bra look in the cgp for your answer. Im correct.

Nope second one is 109 because theres also a hydrogen bond around the carbon atom, its skeletal so you cant see it on the diagram

daaaaaaaaaaaaaaaarn it!! little things like this are gonna mess my mark up :frown:

-completely forgot it was skeletal

Reply 186

tasniaTVXQ

Original post by Richyp22

Nope, you'll get nothing for saying active site thats biology tbh. Marks will be for - So you'll get 1 maybe 2/2

-Poisen coats catalysts surface
- Preventing reactants from adsorbing onto catalysts surface
- Therefore catalyst cant get involved in the reaction

Active sites have been in F331 mark scheme before- pretty sure he will get the mark for it. All catalysts have active sites but yep your three points would be better lol

Okay legit grade boundaries for this paper? Doubt 48/50 will be an A but I do think they'll be high.

Reply 187

krisshP

14

the mark scheme are so annoying and picky!!!! :angry:

Reply 188

CameronLee

6

Original post by tasniaTVXQ

Active sites have been in F331 mark scheme before- pretty sure he will get the mark for it. All catalysts have active sites but yep your three points would be better lol

Okay legit grade boundaries for this paper? Doubt 48/50 will be an A but I do think they'll be high.

It was 49 last June and the paper was harder ...

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Reply 189

tasniaTVXQ

Original post by CameronLee

It was 49 last June and the paper was harder ...

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Omg I think writing 50 threw me off. 49/60 sounds fine o.o

Reply 190

CameronLee

6

Original post by tasniaTVXQ

Omg I think writing 50 threw me off. 49/60 sounds fine o.o

How did you find the test I think I dropped around 8 :s-smilie:

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Reply 191

CrankDatHoe

By far the nicest Chemistry for life exam I have ever seen, super happy. Maybe finally I can get my 90% +. What did everyone put for the comparison of the 'dot-cross' diagram for CO2 and SiO2?

Reply 192

exams567

i wish GB are 48/60. they have gone as low as 46 but i ithink 48 should be good 4 this paper

Reply 193

tasniaTVXQ

Original post by CameronLee

How did you find the test I think I dropped around 8 :s-smilie:

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Aww don't worry! Even losing 8 gives you a comfortable A :smile:

OCR B boundaries always stay roughly the same :smile:

idk I know I dropped 2 or 3 but I guess you always lose marks elsewhere too! :frown:

its done now so don't stress about it :smile:

Reply 194

Mangodepo11

8

Original post by tasniaTVXQ

Active sites have been in F331 mark scheme before- pretty sure he will get the mark for it. All catalysts have active sites but yep your three points would be better lol

Okay legit grade boundaries for this paper? Doubt 48/50 will be an A but I do think they'll be high.

Well I found that shockingly easy compared to the summer, But i tried really hard this time around. In summer it was 49 for an A.

So 49-51, Its out of 60 btw. Im geussing no lower, theres no way they'll drop it lower they only give A's to around 8-9% on people normally so as you can image they dont need low grade boudries to achive that

(edited 11 years ago)

Reply 195

TLittler

2

Only one I didnt get was radioactive decay question even put my hand up to say there was a mistake in the paper. How does a Hydrogen Isotope decay to Helium isotope, this means a proton must be gained? I put beta decay as this was the only one it that could make any sort of sense, but it really confused me

Reply 196

Mangodepo11

8

Original post by TLittler

Only one I didnt get was radioactive decay question even put my hand up to say there was a mistake in the paper. How does a Hydrogen Isotope decay to Helium isotope, this means a proton must be gained? I put beta decay as this was the only one it that could make any sort of sense, but it really confused me

Yes it was beta. Hydrogen 3 has a mass number of three and a atomic number of 1. So during beta decay, a neutron is converted to a proton which makes He isotope. That was hard cause it only mentions that in a small section of chemical ideas that I read time agoo and luckily remebered.

Reply 197

TLittler

2

Original post by Richyp22

Yes it was beta. Hydrogen 3 has a mass number of three and a atomic number of 1. So during beta decay, a neutron is converted to a proton which makes He isotope. That was hard cause it only mentions that in a small section of chemical ideas that I read time agoo and luckily remebered.