OCR Chemistry B (Salters) F334/F335 Exam Thread 2016 (14th/22nd June)

Original post by Kira Yagami

For the isomers did you get 2? I got 2 and named one E and the other Z ?

Cold drawing: The chains are pulled making them straight and more crystalline so chains are closer together and so stronger IMF so mor energy needed to break them etc...

I got two, some seemed so think that since there were 4 marks that it'd be four isomers however I disagree and I assumed it would be two isomers and two marks for labelling them correctly.

There was one hydrogen on the two inner carbons so I didn't think they'd show E/Z isomerism

Reply 382

LewisEdwards1234

I guess if this paper went bad for you the F335 grade boundaries are usually around 81/120 for an A so it's not the end of the world

Reply 383

Dentistxo

Original post by _MAT_

Could of sworn it said put all

No it said two

Reply 384

username1084917

16

Original post by _MAT_

I got two, some seemed so think that since there were 4 marks that it'd be four isomers however I disagree and I assumed it would be two isomers and two marks for labelling them correctly.

There was one hydrogen on the two inner carbons so I didn't think they'd show E/Z isomerism

Yeah it makes sense that there are 2 right?

Reply 385

Original post by thelizzister

lol true, but whatever happens happens, really wanted to think I got those 4 marks (theres still the chance I didn't though :colondollar:

)

I'm sure it didn't specify the number it just asked to put the functional groups present other than benzene

ah fantastic and i'm sure you did

Reply 386

George12411

I swear AQA students don't deal with the BS that ocr manage to creat up each year. Joke of a course

Reply 387

Akalanka25

Original post by IBerrr

Well think about it. If a reactant is removed, this will increase the concentration of the one reactant but also decrease the concentration of the other. If the reactant that increases in concentration was second order then the rate will also increase, however, if the reactant REMOVED was second order, then the rate of reaction will decrease. As we were not told which of the reactants were removed, the mark scheme will most likely require candidates to write 'change' as opposed to 'increase/decrease', although I imagine it will ALLOW 'increase/decrease'

Actually that makes a lot of sense. Here's hoping that the mark scheme is lenient on that as it was such an ambiguous question. I didnt even say it changes, I just said it could increase or decrease

Reply 388

Original post by Kira Yagami

Yeah it makes sense that there are 2 right?

Indeed, based on what we've been taught before this was the logical conclusion for me at least

Reply 389

IBerrr

Original post by yoyo.sat

I dont understand how the bromine number can be 390 or 195 when its meant to be how many grams of bromine in 100 grams of sample, surely it has to be less than 100 grams because its impossible to have 195 g of bromine in 100 g of sample?

I believe you may have read the information incorrectly. The bromine number is the mass (in g) of bromine reacted with 100g of reactant. The bromine is not 100g, the reactant (hexadiene) is 100g which is what allows you to calculate the moles of hexadiene by doing mass/mr. If you think about it, why would a question ask you to find the mass of bromine if it already told you the mass was 100g, and if this actually was the case, the answer would be 100g of bromine, nothing less.

Reply 390

charliexox

For the catalysis one I thought because it was a transition metal it changes oxidation state as it reacts to form an intermediate which is then regenerated ??

Reply 391

KINGYusuf

12

Original post by abdi3412

Am i pilau rice to be aired

Pilau rice is mad fam, allow it it's not even Iftar yet my g. Goodluck still on this akh

Reply 392

KINGYusuf

12

For the homogeneous one did anyone just explain the normal answer like in F331?

Adsorption bla bla bla?

That's what I did lol idk

Reply 393

username1084917

16

So everyone, for the medicine one I said

" Is it safe?"

"Is it better than current medicines being used/standard medicines being used now"

Reply 394

Original post by charliexox

For the catalysis one I thought because it was a transition metal it changes oxidation state as it reacts to form an intermediate which is then regenerated ??

That's for homogenous, some of the stuff still applies though

Reply 395

Lauren2812

12

Original post by Bella09

For the prove in excess question, I worked out the volume of KBrO3 that would have reacted and got something like 66.8cm3 which was less than the 100cm3 supplied so it's in excess??? Would that be wrong bc all I've seen is people comparing moles?

I imagine there are multiple ways to do it so don't worry!

Reply 396

FemaleBo55

17

Original post by Daniel9998

Needed a very high A/A* in this exam as well LOOL.
Full UMS in F335 here I come

OMG SAME HEREE LOOOL!!! For me to get an A I needed at least 80 UMS because and unit 5 I needed a scarp A but I guess I need 120 UMS now for unit 😂
No clue why it was so hard this year!!!

Posted from TSR Mobile

Reply 397

username1084917

16

For the one about volatile substances I said " H+ is in excess so it's conc would not be changing lol and then said because there is less reactants, there would be a lower rate of reactions because fewer collions between particles etc... so rate decreases?

Reply 398

IBerrr

Original post by Dentistxo

No it said two

I can gurantee you it said 'all', pretty sure in bold aswell

Reply 399

Akalanka25