For the titration Q i also got 44 % or something but im unsure about it...didn't you have to take away the moles of something because it said potassium ioide was in excess. Think I did it wrong tbh because normally with back titrations you have to take away the mols reacted :frown:

Reply 45

Nina_85262737

8

Also. I got [HA] = [A^-] for that very very last question.

Reply 46

ThatGuy107

13

Original post by JTofty

Krypton is a noble gas so isn’t electronegative it was bromine

Afraid not, Krypton is indeed electronegative, go check the electronegativity scale

Reply 47

iamjosephvella

8

4.3

Original post by lollypenguin

that's right

Original post by Nina_85262737

What did everyone get for The buffer question??

Reply 48

Nina_85262737

8

Original post by JTofty

4.30 chief

Cool beans.

Reply 49

username3016694

10

Also for Period 4- did it ask for the one with the smallest atomic radius or largest? I thought it was the largest and wrote Ga :/

Reply 50

iamjosephvella

8

Original post by iamjosephvella

4.3

aqa:"cobalt and electrospray ionisation are off the spec"
proceeds to ask 10 marks worth of questions

Reply 51

lollypenguin

18

Original post by JTofty

Krypton is a noble gas so isn’t electronegative it was bromine

a lot of online sources state krypton has a higher electronegativity

(edited 4 years ago)

Reply 52

fopeadedeji

3

It was in the form 0.5I2—> I , so I don’t think so

Original post by CeliaaaWuuu

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

Reply 53

Dreametuber

6

Does 1.77x10^-4 sound familiar to anyone- can’t remebe what question

Reply 54

bsafe86

3

Electro spray ionisation is defo on the spec as it is in the student guide on aqa website

Original post by iamjosephvella

aqa:"cobalt and electrospray ionisation are off the spec"
proceeds to ask 10 marks worth of questions

Reply 55

Spiket

4

Most electronegativity tables exclude all noble gases, but on those that don’t krypton is the most electronegative in period 4. Not sure how aqa expect you to know that.

Reply 56

cheesypizza

9

for ClF3- i remeber getting octahedral shape with bond angle 90

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

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

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

Question about Period 4
Most electronegative- Bromine
Potassium had the smallest 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
Kp doesn't change and units remain the same? People square rooted Kp but I thought that since there wasn't a change in temperature, the Kp couldn't change?
These are all the maths ones (almost) so feel free to add