GCE O Level Chemistry Aftermath Report
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i think i lost 15 mark liao
how do the tonnnes Q and the graph
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why the title suddenly changed
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I change one... This thread will be the official chemistry thread... All other threads will be locked
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lololol i ask again, what is the chemical formula of sodium carbonate? i wrote Na(CO3)2.
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2 moles of Mg form 1 mole of U
U mol -> 10 tonnes/238 = 0.042 mol
so, Mg mol -> 0.042(2) =0.084 mol
Mg Ar -> 24
Mg mass = Mg mol x Mg Ar = 24 x 0.084 = 2.016 tonnes or 2.02 tonnes.
Graph just draw until 150 s ( see tb for speed of reaction- hydrogen produced)
2nd graph draw less steep (cos less conc.) -
Originally posted by Maith:
lololol i ask again, what is the chemical formula of sodium carbonate? i wrote Na(CO3)2.
I thought Na+ and CO32-
Means it should be
Na2CO3
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sodium carbonate's chem formula is Na2CO3
(carbonate has a charge of 2-/ sodium has a charge of 1+) -
Originally posted by eagle:
I thought Na+ and CO32-
Means it should be
Na2CO3
))))): lose 2 marks liao...
oh at the first page got one they ask what's the use of limestone in the blast furnace..I wrote to react with silicon oxide..lol anyhow wack \:
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1st page
copper (radio circuit) = to conduct elec
plastic (on iron) = to prevent iron from rusting
calcium hydroxide (farming) = to neutralise acidic soil
limestone (extraction of iron) = to remove acidic impurities (in a blast furnance)
2nd page
name 1 grp I element eg. sodium
name 1 grp VI element eg. Oxygen
give FORMULA of them combined -> Na2O
explain BRIEFLY:
why grp I elements have same chem properties?
- They all have 1 valence e-
why grp VI elements are non-metal
- they gain 2 e- to become anions, forming noble gas config.
3rd page is flow chart
draw ethene/ ethanol
if not wrong
ethene -> ethane , HYDROGENATION
ethene --polymerisation--> poly(ethene)
ethanol --oxidation--> ethanoic acid
4th pg is mixture elements compounds
5th(?) pg spd of rxn
6th pg ?
7th-8(?) pg METALS
9th pg before essay / flow chart for qual analysis
liquid tt boils at 100 c - obviously /water/
test for nitrate (present) - gas evolved /ammonia/
test for copper (present) - blue ppt /copper (II) hydroxide/
since copper n nitrate present, salt is... /copper (II) nitrate/
give any 1 chem eqn
Cu(NO3)2 (aq) + 2NaOH (aq) -> Cu(OH)2 (s) + 2NaNO3
essay
9(a) nv do
10 (a) titration*** - since sodium carbonate is soluble
cannot be general method***
(b) calculate something
(c) H+ + OH- -> H2O
11 (a) describe fermentation under lab conditions
(b) C6H12O6 -> 2 C2H5OH + 2CO2 + state symbols
(c)Mr of ethanol =___
% of C in ethanol =__ -
die
i wrote 2 tonnes
shit
the curve i never draw till the meet then straight
just enough time to finish section b
overall wasnt hard
bad news is passing up move up
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Originally posted by Occam's Razor:
1st page
copper (radio circuit) = to conduct elec
plastic (on iron) = to prevent iron from rusting
calcium hydroxide (farming) = to neutralise acidic soil
limestone (extraction of iron) = to remove acidic impurities (in a blast furnance)O_O how u know the qn ar? lol
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the tonnes one tin tin got teach me !!
but i no time to slowly tink and do, at the end i just whack the answer as 2.01tonnes.
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how come ur first page diff as mine?
diff syllabus?
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the tonne qn i forgot to times 2
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maith wat is ur syallbus?
5152?
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The Q still fresh inside my head so i rmr
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5152 is cimbine?
5116 and another is teh same paper
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Originally posted by gunner77:
maith wat is ur syallbus?
5152?
5116! :D
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i take the 5152 paper.
anyone same as me?
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i am also taking 5152. I want to ask if Q2 is asking Group 1 and Group 7 or Group 6
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xxhowxx
wats ur answer for the tonnes part?
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I wrote 2.02 tonnes for that question as i got 2.016 tonnes i rounded up. BTW wat was qn 2 asking Part a)
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i wrote 2.01 tonnes. i never round off to 2.02
question2 part a is wat?
u mean the name a element from group I and VI
i put sodium and sulphur.
Na2SO4
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anyone know qn 10 is asking for titration or crystalization?
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i dint do tat question, but i tink its titration.