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AQA A Level Chemistry Paper 1 4th June 2019 Unofficial Markscheme Paper 1

This poll is closed

How many marks do you think you got?

0-104%

10-204%

20-307%

30-4010%

40-5013%

50-6016%

60-7020%

70-8013%

80-908%

90-1004%

100+2%

Total votes: 2687

YellowYellow2

16

Feel free to add yours answers and then I can order them

1.1) Equations- Cs(s)+ 1/2I2(s) and then Cs+(g)+e-+I
1.2) 107 (bit of a debate about this one)
1.3) Perfect ionic model
1.4) 333kJmol-1 and since G>0, its not feasible

Acids and Bases Question:
Kw- 4.57 * 10^-14
4.30
The third box on the table
For Ka- 1.26*10^-5
HA= A-

Question with the Fe complexes
Fe(OH)3(H2O)3
Brown Colour
2[Fe(H2O)G]3+ + 3CO32- => 2[Fe(H2O)3(OH)3] + 3CO2 +3H20
FeCl3? and then equation with 3 Cl-
Fe(H2O)4(OH)2 and green precipitate
For the 6 marker
Co(OH)2(H2O)4 for the octahedral which displayed cis/trans isomerism
Co(en)3 for it displaying optical isomerism
Cis and trans platin for the square planar isomerism
Linear
Tetrahedral

Question about Period 4
Most electronegative- Bromine
Potassium had the largest atomic radius atomic radius due to least number of protons- least attraction between outer shell of electrons and the nucleus
Amphoteric

Titration
Percentage by mass of carbon is 46.4%
To increase the accuracy- use a larger mass of solid or less concentrated thiosulphate
Iodine acts as the oxidising agent?
Its white because it has a full d orbital and so, cannot absorb any light and emits all of it so looks white

Shapes of molecule
The drawing between the molecules with two lone pairs on the oxygen to show a dashed line with the hydrogen
The ethanol has hydrogen bonding but the methoxymethane has dipole-dipole/ van der Waals so as the hydrogen bonding is stronger, more energy is required to overcome the attraction and so, the boiling point is higher
The Pocl3 was tetrahedral and the other one was squareplanar (don't know WHY i thought it was trigonal bipyramid) with a bond angle of 90 degrees

Electrospray Ionisation
Vapourise the sample, pass through hypodermic and hollow syringe, a high voltage terminal and proton gained and I think the equation was P(g) + H+(g) => PH+ (g)
Mass number was 155 because the H+ added an extra one?
Mass of molecule was 169

Kp question
Overall pressure- ranges have been from around 190,000-195,000
Kp was higher with the lower temperature and since a lower temperature favours the endothermic reaction, the forward reaction must be endothermic
Square root the Kp

Halogens
NaCl+ H2SO4 => NaHSO4+ HCl
2NaBr+ H2SO4 => Br2 + Na2SO4
Brown Fumes
Oxidising agent
+1 and -2? was it disproportionation? (I don't think it was)
Ions
AgBr
AgCO3
CO2
AgBr+ Nh3 => [Ag(Nh3)2]+ + Br-

Mass of O2- 1.52g

(edited 4 years ago)

Reply 1

millsarthur1

3

200000 Kp, wrong significant figures x

Original post by Khushi.S

Feel free to add yours answers and then I can order them
I got (in no order)
192000 for the Kp question
169 for the relative molecular mass
750 for the ideal gas law equation
4.3 for the buffer solution
46.4% for the titration
333Kjmol-1 for the entropy
107 for atomisation

These are all the maths ones (almost) so feel free to add

Reply 2

Aadz7

12

I think kw was 4.57 x 10^-14 or something like that

Original post by Khushi.S

Feel free to add yours answers and then I can order them
I got (in no order)
192000 for the Kp question
169 for the relative molecular mass
750 for the ideal gas law equation
4.3 for the buffer solution
46.4% for the titration
333Kjmol-1 for the entropy
107 for atomisation

These are all the maths ones (almost) so feel free to add

Reply 3

CeliaaaWuuu

6

don't you need to multipying the 107 by 2? for the atomisation enthalpy change of iodine.

Original post by Khushi.S

Feel free to add yours answers and then I can order them
I got (in no order)
192000 for the Kp question
169 for the relative molecular mass
750 for the ideal gas law equation
4.3 for the buffer solution
46.4% for the titration
333Kjmol-1 for the entropy
107 for atomisation

These are all the maths ones (almost) so feel free to add

Reply 4

Kallum17

8

I x2 as well

Original post by CeliaaaWuuu

don't you need to multipying the 107 by 2? for the atomisation enthalpy change of iodine.

Reply 5

Aadz7

12

I also did x2

Original post by Kallum17

I x2 as well

Reply 6

YellowYellow2

OP

16

I thought atomisation was already set for 1/2?

Original post by CeliaaaWuuu

don't you need to multipying the 107 by 2? for the atomisation enthalpy change of iodine.

Reply 7

CeliaaaWuuu

6

Original post by Aadz7

I also did x2

I am so happy that I am not alone :excited:

Reply 8

Abdidoodle

6

what was the shape of POCl3 btw??
Ik that ClF3- was square planar with 90degrees

Reply 9

Vin_17

6

tetrahdral

Original post by Khushi.S

I thought atomisation was already set for 1/2?

Reply 10

lollypenguin

18

Original post by Abdidoodle

what was the shape of POCl3 btw??
Ik that ClF3- was square planar with 90degrees

tetrahedral

Reply 11

mynameisandrea4

4

Period 4:
biggest atomic radius Potassium as least nucleus charge and electrons, so least amount of electrostatic attraction between nucleus and electrons.

Reply 12

Maheed

5

I halfed it by 2 for the atomisation one, did anyone get 4.30 for the buffer question as the pH?

Reply 13

Kallum17

8

Original post by Abdidoodle

what was the shape of POCl3 btw??
Ik that ClF3- was square planar with 90degrees

I thought pocl2 was trigonal pyramidal, 4 boding pairs one lone pair.

Reply 14

CeliaaaWuuu

6

Original post by Khushi.S

Feel free to add yours answers and then I can order them
I got (in no order)
192000 for the Kp question
169 for the relative molecular mass
750 for the ideal gas law equation
4.3 for the buffer solution
46.4% for the titration
333Kjmol-1 for the entropy
107 for atomisation

1.1) Equations- Cd(s)+ 1/2I2(s) and then Cd+(g)+e-+I
1.2) 107 (bit of a debate about this one)
1.3) Some covalent character?
1.4) 333kJmol-1 and since G>0, its not feasible

These are all the maths ones (almost) so feel free to add

I think for 1.3 the answer will be perfect ionic model due to no covalent character. because the experimental and the theoretical value are so similar and the theoretical value are base on the perfect ionic model.