When
calculations on TM are done, when do we include the hydrated H2O or
the anhydrous salt? Eg 2013 P2 Qn 2(c)(iii) we use the Mr of
anhydrous salt
2013
Paper 2
Q3(a)(i) can
reagent A be Na metal instead of NaOH?
Q4(a)(i) When we compare between main group and TM can we use NC
increase across the group and SE remains relatively constant to
compare ENC and from there explain the atomic radii? Since all the
elements are in the same period?
2013 Paper
3
Q1(c)(i) When we draw the mechanism do we use equilibrium arrow?
Sincs that is given in the question?
2012 Paper
2
Q2(a)(ii) Can we say that nitrogen containing hydrocarbon is
combusted to produce NO gas?
Q2(c)(i) How do we know that delta G is supposed to be measured in
joules?
Q5(a)(ii) Do we have to describe the mechanism by steps like
nucleophilic attack and regeneration of catalyst in the
mechanism?
2013 P2 Qn 2(c)(iii) - If the question doesn't specify "hydrated",
you've to use the molar mass of the anhydrous form.
2013 Paper 2 Q3(a)(i) - You've only a small chance that Cambridge
might show you mercy and give you that mark, for 3 reasons. 1stly,
Cambridge is testing to see if the student knows that phenol, being
more acidic than alcohols, can be deprotonated just by the use of
NaOH(aq) alone. 2ndly, NaOH is a lot cheaper and less hazardous
than Na. You should always only use the cheaper and safer reagent,
if both reagents have the same effect. 3rdly, beyond the H2
syllabus, Na being such a strong reducing agent, can actually
(under certain circumstances or with certain co-reagents) reduce
the benzene ring (eg. Birch reduction).
Q4(a)(i) - Acronyms are not acceptable by Cambridge in the A
levels. Don't over-use them even in your own self-revision. No,
your answer is relevant only for period 2 and 3 elements excluding
d block metals. For this question, you need to specify that 3d
orbitals (being more diffused) provide relatively poor shielding
for the 4s orbitals electrons, which are consequently more strongly
electrostatically attracted to the positively charged nucleus, of
which Fe and Cu have 6 and 9 more protons compared to Ca.
2013 Paper 3 Q1(c)(i) - Cambridge won't give a damn either
way.
2012 Paper 2 Q2(a)(ii) - You won't get any marks for your answer.
Because in the 1st place by definition of hydrocarbon, there is no
nitrogen present (immediately zero marks for this part of the
question liao). Next, even if some organic fuels contained nitrogen
(eg. amine group, nitrile group, amide group, imine group, etc),
that isn't the main mechanism (which Cambridge is testing you for)
by which oxides of nitrogen are formed. It's the atmospheric N2
which reacts with atmospheric O2 at high temperatures that is being
tested here. Be sure you mention the strong NN triple bond, the
high activation energy involved, and the high temperatures present
in combustion engines.
Q2(c)(i) - If before today you didn't know, after today you know
liao. Yes you're supposed to have memorized this in the H2 syllabus
lah!
Q5(a)(ii) - As long as you draw out the full mechanism correctly
(yes including regeneration of the catalyst), you don't need to
describe anything in words.
