Edexcel Chemistry A-level 2018 paper 2 unofficial mark scheme

Scroll to see replies

How do anti bumping granules stop bumping?

Why can’t distillation be used over reflux to form ethanoic acid

Said ethanol would only oxidised into an aldehyde which would condense and form ethanal as the product instead of being continuously oxidised and recycled to form ethanoic acid

Reply 62

in a fish bowl

Original post by glue.stick

I thought the question said compare and contrast the bromination of benzene and phenol. So I talked about with benzene there needs to be halogen carrier, and benzene undergoes electrophilic sub. For phenol I said milder conditions and it undergoes electrophilic addition. Am i wrong? Was the question explain?

Not wrong you could have explained the reasons for the easier bromination in phenol though

Reply 63

Nuxzy

Original post by Lucasmoss

Can anyone explain what all the numbers they got for the activation energy question? Because I have no idea how i ended up with 800 and something

I got activation energy +157.......

Reply 64

kayan200000

Original post by Zzbc

How do anti bumping granules stop bumping?

Prevents superheating/ localised heating
ALLOW: Violent boiling
OR Promotes smooth/even/uniform boiling
OR Promotes smooth/even/uniform heating

(From Edexcel Unit 6 January 2014 paper)

Reply 65

glue.stick

Original post by in a fish bowl

Not wrong you could have explained the reasons for the easier bromination in phenol though

Thank you for answering. So do you think I will have scored 1 possibly 2 marks?

Just wondering because i thought i had misread the question completely :\

Reply 66

Zaib Malik

Original post by Roe123

Anyone remember the question on pV=nRT which is to find the mass of NaN3??
I rmb it’s sth like this:
140000 x 0.093 m3 = n x 8.31 x (300+273)
mole = 2.73 sth
And then the mass will be 2.73 x 65 =177.45 g???
I forgot the exact no. but ppl said it’s 83 sth but I rmb I put sth larger than 83
Please helpppppoo

The equation in part i. Use that to find the moles of Sodiam azide with the moles of nigrogen

Reply 67

binz

Original post by flamesofsnow

am i the only one who could 50 something grams for the ideal gas one? how did people work it out?

no I got 51 as well. I worked out the no of moles using pV=nRT. then divided the no of moles by 5 and times it by 2. this gave me the no of moles of NaN3. then times it Mr to get mass.

Reply 68

_RobbieL_

Original post by binz

no I got 51 as well. I worked out the no of moles using pV=nRT. then divided the no of moles by 5 and times it by 2. this gave me the no of moles of NaN3. then times it Mr to get mass.

how did you get a 5:2 ratio? I got mine to be 3:2

seeing as the decomposition equation i got was NaN3 --> Na + 3/2 N2

(edited 5 years ago)

Reply 69

binz

Original post by _RobbieL_

how did you get a 5:2 ratio? I got mine to be 3:2

there were 2 moles of reactants and 5 moles of product. 1mole of reactant has same volume as 1 mole of product. if that makes more sense.

Reply 70

Roe123

Original post by Zaib Malik

The equation in part i. Use that to find the moles of Sodiam azide with the moles of nigrogen

Oh ****!! I forgot there was an equation in part i
Do you think I will still get mark for carrying out the mole coz I calculated the incorrect mass😭

Reply 71

Ingram12

Original post by glue.stick

Thank you for answering. So do you think I will have scored 1 possibly 2 marks?

Just wondering because i thought i had misread the question completely :\

yh it did say compare and contrast. I forgot to mention about the halogen carrier needed for benzene which i think should definitely get a mark. Does phenol not also undergo electrophillic sub with bromine though because 3 hydrogens replaced by 3 bromines?
I mentioned about how LP on oxygen delocalized into ring making phenol more reactive as increases electron density of ring increased so reacts with bromine whereas benzene wont (without catalyst) but i guess that is more kind of explaining but will prob still get a mark. Also mentioned how phenol decolourises bromine and benzene doesnt (orange solution remains).

Reply 72

immiehunt

Original post by salporter23

i put the 1000/t and vol on the wrong axis for the graph :frown:

do u think they’ll take marks off if graph is still correct?

I did the same :s-smilie:

Reply 73

_RobbieL_

Original post by binz

there were 2 moles of reactants and 5 moles of product. 1mole of reactant has same volume as 1 mole of product. if that makes more sense.

but the only gas created as a product was nitrogen, sodium is a metal therefore would of been a solid, so the total moles of gas (this is the ideal gas equation) is only that of nitrogen..

Reply 74

binz

Original post by _RobbieL_

but the only gas created as a product was nitrogen, sodium is a metal therefore would of been a solid, so the total moles of gas (this is the ideal gas equation) is only that of nitrogen..

oh, forgot about sodium being solid, then ur probably right then.

Reply 75

zninja3

In the exam we had to write the equation for bomination of phenol or something and it had a line there for Br2 and you had to fill in the number int he front. But there was not lines for HBr, now im confused and now think i didnt balance it properly