AQA Chemistry Unit 1 23rd May 2014 Unofficial Markscheme

you can put 8.93 * 10^-3 right?

I think sooo

5)a)
Substance: Crude Oil
Process: Fractional Distillation [2 marks]

5)b) C12H26(l) + 12.5O2(g) ---> 12CO(g) + 13H2O(g) [1 mark]

5)c)i) Nitrogen oxides are produced in the air when there is enough energy for the N2 and O2 present to combine. At high temperatures, such as combustion of paraffin, with sparks etc., there is sufficient energy for these reactions to take place. [2 marks]

5)c)ii) 2NO + O2 ---> 2NO2 (or NO + 0.5O2 ---> NO2, I guess) [1 mark]

5)c)iii) 4NO2(g) + O2(g) + 2H2O(l) ---> 4HNO3(aq) [1 mark]

5)d)i) C_nH_n+2 [1 mark]

5)d)ii)
Cracking: C12H26 ---> C6H14 + C6H12
Empirical Formula: C3H7
Catalyst: Zeolite [3 marks]

5)d)iii) Dodecane has more atoms in a single molecule, which increases the amount of van-der-Waals forces between molecules (IMFs), so it required more energy to separate these molecules than it does to separate the C6H14, which has weaker VDWs. [2 marks]

5)e) 2,2,3,3,4,4-hexamethylhexane, chain isomerism [2 marks]

5)f) Cl2 [1 mark]

The TlBr one. Can I ask if others put down the reason for the high m.p was due to the giant ionic lattice? It's weird because while it's a metal they asked for shapes just above it. I assume it can form both covalent and ionic bonds depending on the conditions?

The TlBr one. Can I ask if others put down the reason for the high m.p was due to the giant ionic lattice?
It's weird because while it's a metal they asked for shapes just above it. I assume it can form both covalent and ionic bonds depending on the conditions?

TOTAL MARK SCHEME

1)a)i) Proton + Electron = 1.6734 * 10^-24

1)a)ii) Neutron (B)

1)b)i) 20%

1)b)ii) Isotopes only vary the number of neutrons. The electron configurations are the same in both isotopes and this is what determines chemical reactions, therefore they have similar reactions.

1)c) Since Boron is group 3, you'd expect the first 3 to have close values. Probably anything between 4000-8000.

1)d) B+(g) --> B2+(g) + e-

1)e) It takes more energy to remove an electron from a charged ion than and atom, and also the second electron will be in an s subshell rather than p subshell, so it is marginally closer to the nucleus.

2)a)i) mole = mass/Mr, therefore 2.16/241.8 = 0.00893mol (3s.f.)

2)a)ii) (0.00893/4)*3 = 0.00670mol

2)a)iii) PV = nRT question.

P = 100kPa = 100*10^3 Pa
T = 293C = 566K
n = (0.00893/4)*12 = 0.02679mol

V = nRT/P = 0.00123...m^3 == 1.23 * 10^-3 m^3

2)b) Thermal decomposition

2)c) The other products are gaseous, so this would not be mixed in with the solid Iron(III) Oxide.

3)a)i) d-block

3)a)ii) Nickel is a metal. As such, it has metallic bonds. The atoms lose electrons and become ions, creating a sea of delocalised electrons. It is the electrostatic force of attraction between the oppositely charged electrons and ions that holds the structure together. Since these forces are quite strong, it requires a high energy to overcome them - a high boiling point.

3)a)iii) Draw at least six Ni ions with a sea of electrons surrounding them.



3)a)iv) Nickel is ductile due to the facts that the rows and individual atoms are able to roll over each other and form new configurations without breaking the metallic bonds, thanks to the electrostatic attraction between ions and the delocalised electrons. (?)

3)b)i) 1s2 2s2 2p6 3s2 3p6 3d8

3)b)ii) The balancing question. I'm terrible at balancing (didn't have time to do it in the exam, either). Can someone else do it?

4)a)i) Hydrogen Bonding [1 mark]

4)a)ii)


Also, you should have included the partial delta charges - δ- on the N's and δ+ on the H's. [3 marks]

4)b) The boron is electron deficient and the Nitrogen is highly electronegative with a lone pair of electrons. It donates both of its electrons to the Boron, creating a co-ordinate (dative covalent) bond. [1 mark]

4)c)i) Electonegativity is the 'pulling power' and atom has to attract electron density towards itself in a covalent bond. [2 marks]

4)c)ii) LiF (I think there are others, too) [1 mark]

4)c)iii) Unsure. This has been debated a lot. [1 mark]

5)a)
Substance: Crude Oil
Process: Fractional Distillation [2 marks]

5)b) C12H26(l) + 12.5O2(g) ---> 12CO(g) + 13H2O(g) [1 mark]

5)c)i) Nitrogen oxides are produced in the air when there is enough energy for the N2 and O2 present to combine. At high temperatures, such as combustion of paraffin, with sparks etc., there is sufficient energy for these reactions to take place. [2 marks]

5)c)ii) 2NO + O2 ---> 2NO2 (or NO + 0.5O2 ---> NO2, I guess) [1 mark]

5)c)iii) 4NO2(g) + O2(g) + 2H2O(l) ---> 4HNO3(aq) [1 mark]

5)d)i) C_nH_n+2 [1 mark]

5)d)ii)
Cracking: C12H26 ---> C6H14 + C6H12
Empirical Formula: C3H7
Catalyst: Zeolite [3 marks]

5)d)iii) Dodecane has more atoms in a single molecule, which increases the amount of van-der-Waals forces between molecules (IMFs), so it required more energy to separate these molecules than it does to separate the C6H14, which has weaker VDWs. [2 marks]

5)e) 2,2,3,3,4,4-hexamethylhexane, chain isomerism [2 marks]

5)f) Cl2 [1 mark]

6)a)i) 1.23 moldm^-3 [5 marks]

6)a)ii) 71.5% (1d.p.) [2 marks]

6)b) ??? [1 mark]

6)c) n = 2 [4 marks]

Worked Solutions to 6ai, 6aii, 6c.



7)a) TlBr₃^2- is trigonal pyramidal with bond angles of 107 degrees. TlCl₄^3- is square pyramidal. [4 marks]

7)b)

3 b i) I got 3d6 because it was Ni2+...?

4 c iii) I got BH3... Small electronegativity difference...

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How you guys getting 1.23moldm-3. Why are you guys not considering the calcium nitrate

i did the calcium phospahte...not the calcium nitrate...?....Did you get 0.136?

I explained this earlier in the thread. Even though 4s fills up first, they're also the first electrons to go during ionisation.