AQA AS 2016 - CHEM1 (Resit) Unoffical Mark Scheme

e) Shapes question - SF6 = Octohedral , 90 degrees -SF4 = See-Saw shape. Lone pair on the horizontal plane. Angles 90, 120 or 180 degrees. Probably will accept -2.5 degrees off each angle. (6)

For this I wrote 118, only -2 degrees off would I get it??

Posted from TSR Mobile

What u guys think the grade boundaries be??

e) Shapes question - SF6 = Octohedral , 90 degrees -SF4 = See-Saw shape. Lone pair on the horizontal plane. Angles 90, 120 or 180 degrees. Probably will accept -2.5 degrees off each angle. (6)

For this I wrote 118, only -2 degrees off would I get it??

I wrote that as well

January modules when they were around were for the people re taking i believe. looking at the grade boundaries for those, they were lower, around 54.

EDIT: Thanks to everyone who has helped in this thread. If anyone can remember the marks for each question I will add them in for you guys! Also the Bold stuff after some thought are probably the correct answers or something along the lines of it. Good luck to everyone in the rest of their exams

EDIT 2: I've added in marks from what I can remember

Here is my unofficial mark scheme. Anything in bold I am not sure if it's right. So if you have any idea then please tell me so i can add it! If i have missed anything out then aslo let me know!

Section A

1.
a) Relative Atomic mass Definition (2)
b) Magnetic Field (1)
c) - Ions accept electrons -Current is formed which is proportional to abundance (2)
d) Something like 28.065 for the RAM (3)
e) Similarity= Peaks still at original m/z values becuase +1 ions are still formed/
same relative abundance (or same height of peaks) because same sample is used so similar amount of the isotopes are present
-Difference - Peaks at half the m/z values becasue high energy electrons will produce +2 ions (4)

2. (Can't rmember what topic this was. I think it was about Van Der Waals)
a) -Electron Density randomly shifts -Creating areas of +ve and -ve charge on molecule - Attraction between molecules which is intermolecular force/VDW (3)
b) O-H bond big electronegative difference allows for hydrogen bonds. Hydrogen bonds are stronger than VDW. (3)
c) Fractional Distiallation/Heat under reflux will sperate these (1)
d) The Se molecule is larger. This means the VDW forces are stronger between molecules (2)

3. (Questions about Alkanes?)
a) Group is alkane (1)
b) 2,2,4 - trimethylpentane (might accept 2,4,4 - trimethylpentane) (1)
c) C₈H₁₈ + 12.5O₂ ------> 9H₂O + 8CO₂ (2)
d) but-1-ene (1)
e) C₁₄H₃₀ (1)
f) Thermal Cracking. High temp and high pressure (2)
g) Isomers question. Chain isomer = H₂C=C(CH₃)₂ Postion isomer = But-2-ene Functional Isomer = Cyclic Alkane so cyclicbutane (4)

4. (The weird reactions and the shapes question?)
a) Balancing equation I couldn't remember (2)
b) Cu₂(OH)₂CO₃ + 4HCl -----> 2CuCl₂ + 3H₂O + CO₂ (2)
c) Effervescense(1)
d) Cu₃O₈H₂C₂ or in the structural form Cu₃(CO₃)₂(OH)₂ (4/5)
e) Shapes question - SF₆ = Octohedral , 90 degrees -SF₄ = See-Saw shape. Lone pair on the horizontal plane. Angles 90, 120 or 180 degrees. Probably will accept -2.5 degrees off each angle. (6)

Section B

5. (Period 3 stuff)
a) - Ionisation energies increase -Increasing proton number - Similar Shielding -Attraction between outer electron and nuclues gets stronger -The bigger nuclear charge reduces atomic radius (I don't think this point is needed) (4)
b) -Silicon has highest melting point. -Because of macromolecular/Giant covelant structure. -Strong covelant bonds throughout structure. -Requires high amounts of energy to break. (3)
c) The 2 elements that you could've choosed from were Aluminuim because removing electron from 3p shell or Sulphur because of pair repulsion in 3p shell. (2/3)
d) -Element Y is Sulphur. -Large jump in eneries from 6^th to 7^th ionisation enegies -So 7^th electron in inner shell so sulphur must be the element Y. (3)

6. (Calculations)
a) 0.113m³ (3 sig figs needed) (3/4)
b) 1065 Kg or 1.065x10⁶ g (2/3)
c) Percentage yield = 49.3% (4/5)
d) Method 1 because its 100% atom economy. Only producing one product. (1)

Do you think they would accept same no of peaks for 1e?:/

I'd love it if they were 54 as I haven't got any better than that but they seem to be getting higher everywhere and last year was 57. Plus, as everyone retaking are A2 students we're expectantly smarter so the average mark will be higher

Did anyone just get CHO4 for the empirical formula question?

Yes, however, it seems to me that not everyone revised as much as they should have, they took the exam lightly and some people in my cohort dropped at least 20 marks

Remember that this year we don't have the Oxbridge lot, so, it'll still be a normal bell curve. I wouldn't worry!

I think I actually did ..lol

I'm worrying that I forgot to work out the % of Cu in the sample but at the same time didn't think it was needed haha:/

LOL aqa Caught us out in exam conditions - we forgot that it was a copper carbonate and even later in the paper - the p4 one caught me out - easily dropped around 15-17 marks in the paper
Just focus on chem 2 now and the other 4th and 5th uniy exams and we can hopefully save ourselves