Not sure you'd get a mark for any of those points. First point isn't relevant to the experiment unless you said something do to with limewater, solids don't have concentrations, not sure if your last point is too general and not specific to the experiment.

Reply 589

Misslassenza

5

Original post by Ryan03201

Are you sure it asked for the reaction profile of a catalysed reaction?

i think the 3 marks would be for, showing exothermic profile, showing the activation energy and showing where the products and reactants were.

im pretty sure it just asked for the profile of an exothermic reaction and was just talking about catalytic converters which led onto the next question about how catalysts work.

This. ur right . the scientific paragraph talked about the catalytic converters but didnt ask for drawing a diagram with a catalysed reaction.

Reply 590

alz333

Original post by Itachi8

what was the option, was it c or d?

it was d

Reply 591

alz333

Original post by Itachi8

what did guys put for that c4h11i and c4h11br when they why the rate of reaction increase when i is replaced by br or something like that?

this is because the c-i bond is weaker than c-br

Reply 592

Itachi8

can u plz upload paper with unoffocial mark scheme, thank you

Reply 593

Ryan03201

Original post by alz333

yes i could upload it if enough people request it and ill upload it by tommorow

Yeah could you upload it please

Reply 594

F1's Finest

21

for the chlorine concentrations, what did you guys get

Reply 595

Aysha92

2

Original post by James A

for the chlorine concentrations, what did you guys get

3.73 or something around that. You?

Reply 596

EffKayy

16

omg guys chill.. we've got unit 4 next week lol

Reply 597

F1's Finest

21

Original post by Aysha92

3.73 or something around that. You?

how did you get to that. presumably we got the same values for the 10cm3 sample, so how did you then obtain the original?

what i did was do the moles in 10cm3 was multiply it to get it to 250 cm3, then i did

moles * 1000 / 250

how did you do yours?

Reply 598

arnab

11

Original post by usamakhanlodhi

Hye you know for the energy profile diagram, i drew the diagram for a catalysed reaction with two humps(while its supposed to be one)..but still labelled the activation energy,axes, and the enthalpy change correctly how many marks would i get..
For the next question i said
" looking at the diagram above, we can see catalysts work by proving an alternative route with a lower activation energy. With the reactansts reacting to roduce an intermediate compound which reacts with the other reactants to form the final product. The lower activation energy of the catalysed reaction compared to the uncatalysed reaction means that a higher proportion of molecules have energy equal to or greater than activation energy. This leads to a greater proportion of successful collisions so faster rate of reaction"
The 2 qs made up like 6 marks would i lose them all because of my misinterpretation of the question?

errm i dont think u will lose any marks mate. The question bascally asked u to talk about the way a catalyst works, nd by looking at ur answer, i am pretty sure u got 2out of 3.
i only talked abt how a catalyst works nd didnt refer to the graph like they asked......how many marks do have i lost?

Reply 599

Aysha92

2

Original post by James A

how did you get to that. presumably we got the same values for the 10cm3 sample, so how did you then obtain the original?

what i did was do the moles in 10cm3 was multiply it to get it to 250 cm3, then i did

moles * 1000 / 250

how did you do yours?

I got the moles for 10cm3 then timed by 25 to get in 250cm3. Same as u so far.
I then did moles * 1000/10 as the original volume of disinfectant used was 10cm3. The 250 was the diluted volume.

Edexcel chemistry - unit 2 19th january 2012

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