AQA AS Chemistry Paper 1 2018 Unofficial Mark Scheme

My one ersonally was so bad . Looking at these answers make me even more stressful . Does anyone think that the grade boundaries will go down??

I hope so because looking through this thread I barely match to any of the answers haha. I didn’t even finish the paper I didn’t have time 😒

Reply 81

lozzbozz

1

Thank you this is really helpful!
Also did anyone else find this paper hard in comparison to previous past papers? Maybe because its the third year of the spec.

Reply 82

username2912782

13

Original post by lozzbozz

Thank you this is really helpful!
Also did anyone else find this paper hard in comparison to previous past papers? Maybe because its the third year of the spec.

I think a few people in my school didn't like all the maths- they were hoping to get onto the multiple choice but then just kept on seeing more maths questions and got a bit stressed and so it became more difficult. I think the question are getting less straightforward as more papers happen since the exam boards are exploring the question difficulty, however I feel like we're lucky: I expect that next years paper will be even more difficult.

Reply 83

lozzbozz

1

I did and i know others that did as well :smile:

Original post by 12tastani

Also did anyone else get -2 Kj mol^-1 for the Change in Enthalpy because that’s what I got and I feel like it’s wrong

Reply 84

rafakl

11

Does anyone know what Q5-8 were about

I remember there being an ideal gas equation and question about whether the Mr would be smaller or bigger

Overall I think this paper was extremely hard

Reply 85

Banshee123

16

Original post by rafakl

Does anyone know what Q5-8 were about

I remember there being an ideal gas equation and question about whether the Mr would be smaller or bigger

Overall I think this paper was extremely hard

naa dont remember, what q did you struggle with

Reply 86

rafakl

11

Original post by Banshee123

naa dont remember, what q did you struggle with

Mainly the maths questions in general.i made such stupid mistakes and clearly lost a lot of marks

How did you find it?

Well I’ve failed

OP

Original post by psc---maths

I put 50 but ngl I semi guessed.

Original post by martinii

Does anyone know what the 60cm and 30 cm gas mulitpile choice question was and the answer. Think I put 40 or 50

You can calculate it using stoichiometry. iirc, it was 1 : 3 : 2 where 2 was the products, 1 was the 30cm^3 and 3 was the 60cm^3 gas.
The 30cm^3 is in excess because 1 mole of the 60cm^3 gas is 20cm^3 which is less than the 30cm^3 gas.
You form 40cm^3 of the products + 10cm^3 of excess = 50cm^3 in total.
Hope that helped... It's a very bad explanation :tongue:

Reply 89

username2912782

13

Original post by nyxnko_

You can calculate it using stoichiometry. iirc, it was 1 : 3 : 2 where 2 was the products, 1 was the 30cm^3 and 3 was the 60cm^3 gas.
The 30cm^3 is in excess because 1 mole of the 60cm^3 gas is 20cm^3 which is less than the 30cm^3 gas.
You form 40cm^3 of the products + 10cm^3 of excess = 50cm^3 in total.
Hope that helped... It's a very bad explanation :tongue:

Yeah- I did that in my head since I got the maths just was unsure on whether the chemistry was true. Thanks for making the mark scheme!

Reply 90

JonM2412

1

Hi this isn’t about the paper yesterday but I’m really struggling with some past paper questions for Paper 2 and wondered if anyone would be able to help.

1) analysis of a sample of a chemical with formula C22H30N6O4S, showed that it contained 0.0195 mol of carbon. What mass of nitrogen was present in the sample?
A = 0.041g
B = 0.057g
C = 0.074g
D = 0.420g

2) (someone did explain a question like this already but I’m still a bit confused). What is the total volume of gas remaining after 20cm3 ethane are burned completely in 100cm3 of oxygen? All volumes are measured at the same pressure and the same temperature, which is above 100 degrees Celsius.
C2H5 + 3.5O2 -> 2CO2 + 3H2O
A = 40 cm3
B = 100 cm3
C = 120 cm3
D = 130 cm3

Thank you very much :biggrin:

!!

I also found the first paper really hard like most people on here!

Reply 91

Laurenpaige1212

11

Original post by rm1029

Na has more shielding as it is a new period, therefore F is smaller

Na doesnt have more shielding because the ions had the same electron configuration. But Na has more protons, making Na smaller

Reply 92

Banshee123

16

Original post by rafakl

Mainly the maths questions in general.i made such stupid mistakes and clearly lost a lot of marks

How did you find it?

alright what did you write for the 6 marker

Reply 93

nyxnko_

OP

20

Original post by psc---maths

Yeah- I did that in my head since I got the maths just was unsure on whether the chemistry was true. Thanks for making the mark scheme!

No problem :thumbsup:

Original post by JonM2412

Hi this isn’t about the paper yesterday but I’m really struggling with some past paper questions for Paper 2 and wondered if anyone would be able to help.

1) analysis of a sample of a chemical with formula C22H30N6O4S, showed that it contained 0.0195 mol of carbon. What mass of nitrogen was present in the sample?
A = 0.041g
B = 0.057g
C = 0.074g
D = 0.420g

2) (someone did explain a question like this already but I’m still a bit confused). What is the total volume of gas remaining after 20cm3 ethane are burned completely in 100cm3 of oxygen? All volumes are measured at the same pressure and the same temperature, which is above 100 degrees Celsius.
C2H5 + 3.5O2 -> 2CO2 + 3H2O
A = 40 cm3
B = 100 cm3
C = 120 cm3
D = 130 cm3

Thank you very much :biggrin:

!!

I also found the first paper really hard like most people on here!

Send me a PM and I'll try and explain it as best I can.

Reply 94

pxoe1

1

it was na lost an electron so same number of shells. na has more protons so it attracts orbital electrons closer so the answer was B (small na big f)

Reply 95

Amirarif4801

4

I've heard some people get the actual exam paper if anyone does I'd appreciate if you could dm me

Reply 96

mathsguy5503

7

Original post by 12tastani

Also did anyone else get -2 Kj mol^-1 for the Change in Enthalpy because that’s what I got and I feel like it’s wrong

yep i got that too
like one person said it was 800 or -4 everyone else thinks iits -2 including me
anyone care to explain the particle question with the mass
im not sure i rerranged the equation then i used avagrdos constant got the moles then got the mass

Hopefully

MCQs:
10. Ammonium chloride contains all three kinds of bonding (covalent between N and three H, dative between NH3 and the 4th H and ionic between the ammonium ion and the chloride ion)
11. 6g of N gas is 0.429 mol of atoms, each with 7 protons. So 0.429 x 7 x Avo = 1.8 x 10^24
12. Melting point? Cos atomic radius consistently goes down, electronegativity consistently goes up, and first ionisation energy would have dips for Al and S
13. Haven't got enough Fluorine for all the nitrogen to react. Fluorine decreases from 60cm3 to 0. 2/3 of the Nitrogen will react so from 30cm3 to 10cm3. The reaction will make 2/3 of the amount of NF3 as fluorine, so 40cm3. So the total final volume will be 50.
14. Magnesium is used to reduce TiCl4
15. Barium sulfate is insoluble so you can use it for X-rays of intestines etc
16. H2SO4 acts as an oxidising agent. (Br ions aren't reduced: ox state goes from -1 to 0; there's no hydrogen bromide formed - though there would be HF or HCl made if it were sodium fluoride or sodium chloride; and there's no hydrogen sulfid formed)
17. Magnesium hydroxide is taken for indigestion
18. Phosphorus has the highest 1st IE (dips for Al becaus of 3p and sulf because of pairing electrons)
19. 150g of ammonia is 150/17=8.824 mol. Then double it cos it's in 500cm3
20. Invert the volumetric flask (ensure your solution is homogenous)
21. Rinse the conical flask with water: you'll still have the same number of mols of H+ in the flask when you put your acid in and no leftovers
22. Improve uncertainty by using less concentrated alkali in burette
23. Gloves for battery acid
24. Red to yellow