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CHY3H Unofficial Mark Scheme June 2012

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Reply 80

Phteven

Original post by James_01

Just because i go to the best school in the Country and you go to some ****ty school thats so bad even your mum wouldn't teach there doesn't mean you need to get angry.

Ohhh, you stuck up arrogant little ****. Who cares that you go to the best school in the country? We get examined on the same thing, we get the same grade boundaries. Stop thinking you're better than everyone simply because your parents can afford a private school. It's people like you that make intelligent people look arrogant.

Reply 81

GwuanGwuan

prob looking aaroun 37 to get full ums?

Reply 82

jones2596

For the question about 100 degrees do you think I could get the mark for saying:

As the students could already see the trend in solubility from the results they had already got.

Reply 83

Sara_A

I found that paper quite good...according to this unofficial mark scheme got around 40 marks...guessing the grade boundries is going to be HIGH!!!

Reply 84

TheSnail

Original post by Zigggyy.

HEY! :')
How are you?

omg, the weather <3

Yeah, I was thinking 32-24 probably :')

fine thanks, yourself? Pop over to the year 11 thread!

yeh jeeeez it was so hot in the exam hall

Reply 85

michelfish

Original post by jones2596

For the question about 100 degrees do you think I could get the mark for saying:

As the students could already see the trend in solubility from the results they had already got.

you needed to say the water would boil / evaporate

but it's only one mark :smile:

Reply 86

Jigglypuff786

My UMS Predictions:

39: 100 UMS
36: 90 UMS
32: 80 UMS
28: 70 UMS

Reply 87

OllieWolly

Wasn't the test for chlorides wrong? I said chlorides werent present as although a white precipitate was formed with silver nitrate the student didnt add nitric acid beforehand and I read somewhere that if CO3 ions are present too then then results are affected if just silver nitrate is added or something :s-smilie:

Reply 88

flumpyfi

Hey! I thought it was a fair paper, guys! :smile:

Can someone please tell me if I’d get the mark for these dodgy answers:

Why the student was surprised at the graph? (1 mark)
Because the solubility increased as the temperature increased but decreased when the temperature reached 68 degrees – the solubility rose then fell.

2a) (Alkali metal properties) (2 marks)
-Very reactive
-Low melting points and boiling points

3a) (Properties of transition metals) (2 marks)
-Malleable so can be easily shaped into a ring.
-Very unreactive so will last longer.

4b) (pH of weak acids and strong acids) (2 marks)
-Weak acids have a higher pH than strong acids BECAUSE a strong acid completely ionises in water forming H+ ions whereas a weaker acid only partially ionises forming H+ ions.

Reply 89

PoorLoser

i got around 37 according to this mark scheme!
and i only started revising at 5 this morning! gosh i got lucky it was an easy exam! :P

Reply 90

nyami001.303

I think I got around 36/37. Considering that this was such an easy paper would it still count as an a*?

Reply 91

umar ali

**** for the 12g i put 3.33...
well all my class got 3.33 grams?????

how do you work it out pleasssseee help :frown:

Reply 92

michelfish

Im making some amendments :smile:

lol

1a) Magnesium ions from the dissolved magnesium sulfate make the water hard (1). When sodium carbonate is added the sodium ions dissplace the magnesium ions(1) the magnesium forms insoluble magnesium carbonate taking the magnesium ions out of the solution (1).
b) Result is anomalous / doesn’t fit general pattern (1)
c) Water would boil (1)
ii) 68 ^oC (1)
c) straight lines (1) solubility decreases after 68 ^oC (1)
2 a) They are metals (1), react with water to form alkali's (1) highly reactive (1) 1 electron in outer shell (1) (2 max)
b) Two elements in same place (1), some elements in same group had different properties (1), pattern falls apart after 18 elements (1) metals with non-metals (3 max)
c) Left gaps (1) ordered the elements in increasing atomic mass (1)
3 a) unreactive (1) hard (1) shiny (1) malleable / ductile (Max 2)
b) All have same number of outer shell electrons (1) because 3rd shell is being filled (1)
4 a) Hydrogen ion (1) H⁺ (1) (1 max)
b) strong acid fully ionises(1) weak acid partially ionises(1)
c) i) to give the correct end point (1)
c) ii) 0.61 mol/dm3 (3)
ii) 12g (2)
5 a) i) Bubble gas through limewater (1) and limewater should go cloudy (1)
ii) Wrong (1) as white precipitate did not dissolve in excess sodium hydroxide (1)
iii) Wrong (1) as chloride ions were added in test 1 / hydrochloric acid (1)
b) i) Atomic Absorption Spectroscopy (1), Mass spectrometry (1) MS (1) AAS (1) (Max 1)
ii) more precice (1)
6. so higher force of attraction between outer shell electrons and nucleus (1), so electrons gained more easily (1) less sheilding (1)
7 a) -810 kJ/mol (3)
b) More energy released by bond making (1) than used for bond breaking (1)
c) provides activation energy (1) enough energy for succesful collision (1) (max 1)

(edited 11 years ago)

Reply 93

Epic Flawless

I have a feeling that the conclusion for 5b iii) was wrong because they had used hydrochloric acid which contains chloride ions. Therefore, the silver nitrate used produced a white precipitate only due to the chloride ions in the HCl. Hence, we are not sure if the egg shell contains chloride ions.

Reply 94

Aarongreatbanks

Original post by Fordey

5aii) what does ammonia gas have to do with the question it was aluminuim?

Don't ask, i messed up there i fought they were tyring to trick us using the test for nitrates

Reply 95

Lash

...

(edited 10 years ago)

Reply 96

Cubic

What was question 2a?
2b) Do I get a mark for saying that he didn't leave gaps?
3a) Do I get a mark for saying that they're malleble so can be shaped into a ring.
3b) How many marks for "When the fourth energy level fills up the electrons carry on adding on a lower energy level up until 18 so there are ten more spaces due to the orbital configuration (Carries on with 4s instead of d orbital)." Yeah, kind of blagged it.

Reply 97

PhoenixLament

For 5a iii) I put that it was wrong, the test for halide ions (chloride ions) uses nitric acid and silver nitrate solution, the student had used hydrochloric acid, therefore the conclusion is that it may not be chloride ions?

I also got wrong for 5a ii)

And depending on 5a iii, i think i got about 40/45