(Original post by TheBigDog)
This is Section A, obviously loads/most are wrong because I thought this was a ridiculously hard exam, and a lot of it unrelated. I still don’t think boundaries will change too much because AQA aren’t like that, 70 for an A i reckon. Everyone edit and let’s try and come up with a proper mark scheme
Question 1 is 9 marks
1a) Why is Phosporous Oxide stored in water? – Reacts violently in air
b) Why P4O10 not P2O5? – P4O10 is it in its most stable form under standard conditions
c) Equation = P4O10 + 6H2O = 4H3PO4
pH = 0
d) equation for MgO + H3PO4 – No idea
e)Why can you use excess MgO? Because H3PO4 is a strong acid
f) Why is NaOH an environmental risk? Strong alkaline harms fish?
Question 2 is 7 marks
2a) Equation – G = H – TS
b)Gradient = 0.1 Units = J K mol-1 Symbol = S
c) Why is significance of temperatures below the temp line – delta G is negative so reactions are feasible
d) Why does curve slope? – Change of state, freezing.
Question 3 is 10 marks
3a) delta H =
b)Delta S =
c) T = 700 K? Can’t remember the other 2 but they gave this temperature.
d) why would NO2 not form? – Not 700K
e) N2 + O2 = NO2
f) same number of moles so small entropy so small TdeltaS
Question 4 is 12 marks
4a) Define enthalpy of electron affinity – Enthalpy change when 1 mole of electrons added to an isolated atom in the gas phase
b) Why is F- more electronegative – more shells so more and further from nucleus
c) Why does F- have more negative enthalpy of hydration? No idea
d) Calculation – can’t remember I got 900 something I think
e) Why is it always feasible – delta G always negative because entropy positive and enthalpy change is negative?
f) Can’t remember but it was 2 marks
Question 5 (a disgrace) was 17 marks
5a) Weakest oxidising agent – CdO(OH) because it was most negative.
b) emf = 1.1? can’t remember
c) Equation – cant remember
d) Carbon anode – conduct electricity
e) Essential property of porous cover? – Inert
f) Why leakage? Ions used up
g) +3 and reverse equation
h) Environmental problem? More waste/to landfill
Two ethanol (wtf) fuel cell questions
I) Carbon neutral as no net emission into atmosphere as ethanol comes from plants that photosynthesise.
Question 6 was 10 marks
6a) Coordinate bond
b) O atom acts as Lewis base and donates electrons
Metal ion acts as Lewis Acid and accepts electrons.
c) 180 degrees
d) ratio 3:5 and calculation – no idea
Someone else do section B??