AQA AS 2016 - CHEM1 (Resit) Unoffical Mark Scheme

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

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
b) Magnetic Field
c) - Ions accept electrons -Current is formed which is proportional to abundance
d) Something like 28.065 for the RAM
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

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
b) O-H bond big electronegative difference allows for hydrogen bonds. Hydrogen bonds are stronger than VDW.
c) Fractional Distiallation will sperate these
d) The Se molecule is larger. This means the VDW forces are stronger between molecules

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

4. (The weird reactions and the shapes question?)
a) Balancing equation I couldn't remember
b) Cu₂(OH)₂CO₃ + 4HCl -----> 2CuCl₂ + 3H₂O + CO₂
c) Effervescense
d) Cu₃O₈H₂C₂ or in the structural form
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.

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)
b) -Silicon has highest melting point. -Because of macromolecular/Giant covelant structure. -Strong covelant bonds throughout structure. -Requires high amounts of energy to break.
c) The elements that you could say were Aluminuim because removing electron from 3p shell and Sulphur because of pair repulsion.
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.

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

Electric field accelerates, hence the reference to velocity, the magnetic field deflects. I'm afraid that you're wrong

Do u think saying heat under reflux instead of fractional distillation would get u marks since it was two different compounds that were not alkanes with relatively low boiling points.

I am not so sure. That does sound like a suitable way of doing it.

Do u think saying heat under reflux instead of fractional distillation would get u marks since it was two different compounds that were not alkanes with relatively low boiling points.

I wrote 'Thermalytic' instead of 'Thermal' for the cracking question, would that be accepted? Also, for the last Atom economy question I just put that 'Method 1 because only one product is produced' - I didn't write about it being 100%, would I still get the mark or? Thanks.

Well in method 1 both equations lead to only 1 product so I don't know how that is not 100% atom economy. What poducts are lost? They all go to make 1 product. That's 100%.

I thought that the first step had 2 products, of which the P4O10 was the minor product?

posted from tsr mobile

what u guys think the grade boundaries be??

a - 68
b - 63
c - 57
d - 70
e - 54

You chat ****

Do u think saying heat under reflux instead of fractional distillation would get u marks since it was two different compounds that were not alkanes with relatively low boiling points.

I thought that!!!! They weren't hydrocarbons so I just said distillation, instead of fractional distillation. I should have put reflux too omg, that's what I meant :l

You chat ****

I also didn't wanna write fractional distillation because of this! I can't remember the exact wording but
I wrote something like heat the mixture to 6 degrees (lol) because that was the boiling point of one of them so this would like evaporate off? Lmfao

Mr of P is 31 though so the answer in the end should be 0.451/3 metre cubed and many people have got this answer