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AQA CHEM5 unofficial MS

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Original post by thomaarrss
did the hydrogen oxygen fuel cell have to be in any order?!! Did it say positive negative electrode because i just did whatever order?? how many marks you think ill loose?


It definitely asked for positive electrode 1/2 eq and negative electrode 1/2 eq separately, but I don't know the specific order.

I reckon you probably put down the correct half eq with the correct electrode (ox = negative, red = positive) but can't recall this because its such a minor ting

If you genuinely just wrote them in any order, its 50/50 chance you got them in the right order so 1/3 if you got the overall eq right

2/3 if youre luckyyyyyyyy and theres some sort of error carried but thats just optimism ngl
Original post by emilies18
what do you think the grade boundaries will be like?


isaisababy and a few others methinks came up with predicted grade boundaries, its been pasted to the bottom of the OP
Original post by hi-zen-berg
isaisababy and a few others methinks came up with predicted grade boundaries, its been pasted to the bottom of the OP


sorry.. whats the OP?
image.pngRegarding the solubility of MgCl2(s):

The answer is in fact the solubility will increase with temperature. The question stated itself that solubility is defined as the amount of solute available to dissolve in a solvent ( in this case water ). Hence by the reverse reaction due to exothermic enthalpy of solution, more magnesium chloride will be produced, hence increasing its solubility.

I have attached an image showing solubility (per 100g) of MgCl2, increasing in increments of 10 degrees kelvin.
Original post by hi-zen-berg
isaisababy and a few others methinks came up with predicted grade boundaries, its been pasted to the bottom of the OP


I reckon it will just be the same as last years paper, people always make stupid mistakes
Original post by emilies18
sorry.. whats the OP?


Original Post
Original post by RefusedAccess
image.pngRegarding the solubility of MgCl2(s):

The answer is in fact the solubility will increase with temperature. The question stated itself that solubility is defined as the amount of solute available to dissolve in a solvent ( in this case water ). Hence by the reverse reaction due to exothermic enthalpy of solution, more magnesium chloride will be produced, hence increasing its solubility.

I have attached an image showing solubility (per 100g) of MgCl2, increasing in increments of 10 degrees kelvin.


That's quite soliddddddd i think youre right there
Does anyone know what the highest grade boundaries have been before?
Original post by hi-zen-berg
It definitely asked for positive electrode 1/2 eq and negative electrode 1/2 eq separately, but I don't know the specific order.

I reckon you probably put down the correct half eq with the correct electrode (ox = negative, red = positive) but can't recall this because its such a minor ting

If you genuinely just wrote them in any order, its 50/50 chance you got them in the right order so 1/3 if you got the overall eq right

2/3 if youre luckyyyyyyyy and theres some sort of error carried but thats just optimism ngl


ffs! just thought it was half equation1 and 2 like usual... i put hydrogen first! do you know if delta G had to be any significant figures?????
Original post by vish.handa
I put sulfur for the first question, I'm guessing i'd still get covalent mark but was there anything that specified it be p4O10? Dont think I read it properly


It said at the very top, this question is about period 3 from sodium to phosphorus, very cheeky
It said that it was looking at elements Na->P, I made that mistake at first too!
Reply 51
Avatar for mgill17
mgill17
6
For marks for each question-
1) Periodicity - 12 Marks
2) Born-Haber Cycle - 8 Marks
3)Enthalpy of Solution - 6 marks
4) First EMF Q - 11 Marks
5) Hydrogen Oxygen EMF thing - 9 marks
6) Contact Process - 14 marks
7) Cr questions - 12 Marks
8) Cobalt Chemistry -12 marks
9) Colorimetry/Purification Calculation Q - 16 Marks
Anyone know if for the entropy one you needed to half the values, seeing as entropy and enthalpy are per mole??? i halved but literally no one else did
would i still get a mark if i put p4o10 as the element identified and not P
please someone tell me I'm really worried
Reply 54
Avatar for irendeep
irendeep
i thouhght when calcuating delt H and delta S u would need divide by 2 am i wrong ?
Reply 55
Avatar for mgill17
mgill17
6
Original post by charanjittt
would i still get a mark if i put p4o10 as the element identified and not P
please someone tell me I'm really worried

It said ELEMENT so probably not. Also the following part said the equation with the OXIDE of the element you named so they assumed you named the element.
You'd still get the bonding mark and equation mark provided they are right
Original post by thomaarrss
ffs! just thought it was half equation1 and 2 like usual... i put hydrogen first! do you know if delta G had to be any significant figures?????


i think they normally if an answer is 1.23456789 they will say "answer which rounds to 1.23" in markscheme you're probably fine there. i think ISA/EMPA and Mr is where they are picky about dp/sf
Original post by mgill17
For marks for each question-
1) Periodicity - 12 Marks
2) Born-Haber Cycle - 8 Marks
3)Enthalpy of Solution - 6 marks
4) First EMF Q - 11 Marks
5) Hydrogen Oxygen EMF thing - 9 marks
6) Contact Process - 14 marks
7) Cr questions - 12 Marks
8) Cobalt Chemistry -12 marks
9) Colorimetry/Purification Calculation Q - 16 Marks


rock solid thanks
Reply 58
Avatar for Estoriel
Estoriel
Can someone explain why does the E.M.F increase with pressure?
I think I got 87 in this and Unit 4 - any UMS predictions? Take in mind i think I got 46 in EMPA

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