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AQA AS Chemistry 26th May 2017 Unofficial Mark scheme

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Reply 20

chelseafc141

Original post by student1444

I think I got 360
Was this the N-H bond Q?

Yes

Reply 21

brumtown0121

A2 student here, curious on what the hardest question was?

Reply 22

quietpeople_x

Original post by hafsa473

This is the unofficial mark scheme for AS Chemistry 7404/01

4050kg rocks - answer is around 112 tonnes I think, but some people got 693

6 marker on improving methods

Equilibrium question on P, Q and R - 0.97

Enthalpy question - around ~391 kj/mol
Q = mc∆t --- 50 × 4.18 × 31.7 or something

concentration of sodium nitrite in g mol^-1
I got 3.71 g mol^-1

Reply with anything you remember so I can add to this mark scheme!!

How did you do the equilibrium constant question what was your quadratic formula?

Thanks for the help

Reply 23

Rajan17

Original post by student1444

I think I got 360
Was this the N-H bond Q?

I got that!

Reply 24

chelseafc141

Were the grade boundaries that were set last year low purely because people found it difficult or was the fact they were the first year sitting the new spec a significant influence?

Reply 25

hafsahassan131

i probably failed omg
i got 19.3 for the concentration of sodum nitrile
390 for bond enthalpy
-91.1 for the q m c t questions

Reply 26

student1444

Original post by chelseafc141

Yes

yeah i think i got 360 which seemed right because the next question was why was this value different from 388 which was close lmao

Reply 27

Inteha

Original post by J__

Good luck for A2 :smile:

Thankssss

)

Reply 28

ScrewTheExams

Original post by brumtown0121

A2 student here, curious on what the hardest question was?

Everything

Reply 29

Minawembly

Original post by J__

I got 391 for both too, thought I was tripping in the exam lol :biggrin:

& I got 963 tonnes I think, something around that

Hello,

I got -391 for the first one and then 391 for the second one???

What did you all do for the balancing rock equation??
I got something like 4cu2..., and a lot of 1 cu etc

I said magnesium has higher first ion action energy
I agree with kc
For the q=mct I got that zinc was not in excess,

(edited 6 years ago)

Reply 30

Minawembly

I agree with kc with 0.9..
What did you all get for the balancing rock equation???
Did you all get a lot of one???

Reply 31

tippypro

How many marks was the rock calculation?

Reply 32

quietpeople_x

Original post by Minawembly

I agree with kc with 0.9..
What did you all get for the balancing rock equation???
Did you all get a lot of one???

how did you get 0.9something?

Reply 33

Minawembly

Original post by tippypro

How many marks was the rock calculation?

4 marks
But you will get a lot of marks for calculation.
The only thing is that if Turk balancing was worng then you whole calculation would be wrong because you had to use molar ratio (at least that's what I did)👁

Reply 34

Minawembly

Original post by quietpeople_x

how did you get 0.9something?

I got the expression for R as 2x

So kc= (2x)^2/(1-X)^2

Kc= 3.6 I think
So I square rooted it and then worked from there.

The volume was 1dm^3 so it didn't affect my answer
Hope that helps

Thanks guys!

What were the two enthalpy questions?

Reply 37

ScrewTheExams

Original post by hafsa473

This is the unofficial mark scheme for AS Chemistry 7404/01

First questions -
Configuration of Fe2+ ----- 1s2 2s2 2p6 3s2 3p6 4s2 3d6
Cl- ------ 1s2 2s2 2p6 3s2 3p5

1 b) which has the lower first ionisation energy, aluminium or (magnesium?) ---- aluminium

There was a question on bonding which gave four different molecules. I think there were two tetrahedrals, there was BeCl2 which is linear (I think) and a trigonal planar, I believe. I think the only one with permanentent dipole dipole forces was Ch3Cl (but I could be confused with an MCQ on bonding)

A MCQ asked which of the products is note formed from a redox reaction between sodium iodide and sulfuric acid. I believe the answer was NaHSO4.

4050kg rocks - answer is around 963 tonnes

6 marker on improving methods

Equilibrium question on P, Q and R - 0.97

I got the expression for R as 2x
So kc= (2x)^2/(1-X)^2
Kc= 3.6 I think
So I square rooted it and then worked from there.

Enthalpy question - around 391 kj/mol

Q = mc∆t --- 50 × 4.18 × 31.7 or something
Overall enthalpy change is -155.9

What was in excess? Magnesium

concentration of sodium nitrite in g.dm^-3.
I got 3.71 g mol^-1

Reply with anything you remember so I can add to this mark scheme!!

I feel like Hitler:

https://www.youtube.com/watch?v=FQkeN15Vjpg

(edited 6 years ago)

Reply 38

Minawembly

Original post by ScrewTheExams

I feel like Hitler:

https://www.youtube.com/watch?v=FQkeN15Vjpg

Did it ask for the reactant in excess or not in excess, I know for a fact I got magnesium as excess but i I think I wrote zinc because I thought it asked for not in excess 😬

Reply 39

ScrewTheExams

Original post by Minawembly

Did it ask for the reactant in excess or not in excess, I know for a fact I got magnesium as excess but i I think I wrote zinc because I thought it asked for not in excess 😬

The answer was magnesium you must have misread mate :/ Don't worry, I messed up too and so did everyone/majority in my class lol

How do you do that question btw? Do you just find the moles of each and the one that has more moles you say it's in excess? That's what I did, I hope I got the marks because I had no clue what I was doing lol :biggrin: