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Edexcel GCE AS Chemistry Unit 1: 22nd May 2015 + Unit 2: 02nd June 2015

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What was the reaction?

I said double the atomisation was correct

I can't remember, but the ions were not in the same molar ratio so don't think you could cancel some of them out? it was nitric acid and sodium carbonate I think

Reply 1181

C0balt

Original post by frozo123

I can't remember, but the ions were not in the same molar ratio so don't think you could cancel some of them out? it was nitric acid and sodium carbonate I think

I think it was CO3 2- + 2H+ ==> CO2+H2O

Reply 1182

Medically

How many marks was the relative abundance about drawing the peaks?

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Reply 1183

rasil23

Original post by Medically

How many marks was the relative abundance about drawing the peaks?

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4 marks

Reply 1184

C0balt

Original post by Medically

How many marks was the relative abundance about drawing the peaks?

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Four

Reply 1185

urkadee

Original post by Nautic4l

Also WHY is there a vaccuum in a mass spec..?

To prevent ions reacting with any air particles.

Reply 1186

GrandMasti

For the vacuum one, could you say to prevent air molecules colliding with the ions?

Reply 1187

DesignPredator

Original post by Nautic4l

Didn't do it :tongue:

I did calculations in the middle but no final answer.

Errors in that guy's drawing? And why + on the C? anyone?

Wrong direction of arrow
Partial charges
Chlorine atom should be chloride ion

Carbon lost an electron to Cl so it is now electron deficient, positive as one less electron but same number of protons.

Reply 1188

lfcrules

How did you writw the structural formula i wrote ch2ch2 and ch2brch2br

Reply 1189

Nautic4l

Original post by C0balt

I think it was CO3 2- + 2H+ ==> CO2+H2O

OOH was that the 3rd option so C??

Reply 1190

tan030

Guys, u know that question where you had to fill in the Hess cycle and state the enthalpy change, what did u guys put? I got a +ve value like 178, since thermal decomposition is endothermic. Also, what was the multiple choice answer for which one isn't a reason for why a yield is less than 100%? Thanks

Reply 1191

Nautic4l

Original post by DesignPredator

Wrong direction of arrow
Partial charges
Chlorine atom should be chloride ion

Carbon lost an electron to Cl so it is now electron deficient, positive as one less electron but same number of protons.

What do you mean partial charges? And which one was the wrong arrow? (I said the Cl-Cl one)

Such a guess!

Reply 1192

C0balt

Original post by Nautic4l

OOH was that the 3rd option so C??

I don't remember

Reply 1193

Medically

Original post by C0balt

Four

Noway, it's not 4 marks

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Reply 1194

urkadee

Original post by Faaiz Shah

U had to work backwards.

250 x 4.18 x 25 = blah Joules
Blah /1000 = blah/1000 kj
Moles of cao mass/40.1 +16

And we know that blah/1000 divided by moles of CaO = -197 or whatevr the wuestion said... Reaarange...
Easy 7.45 . I dunno why ppl halved it

Why did you use 250? 250 was in excess so that was unknown.

Reply 1195

tan030

That exam went pretty well I think. Though, I wonder if the boundaries could be 68-70 for an A due to the number of simple questions and the gcse stuff related to electrolysis

Reply 1196

C0balt

Original post by Medically

Noway, it's not 4 marks

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The spectrum drawing was definitely four marks
Probably one for drawing five peaks
One for 81 and 71 being the same height
And something to do with heights or drawing at correct number

Reply 1197

DesignPredator

Original post by Nautic4l

What do you mean partial charges? And which one was the wrong arrow? (I said the Cl-Cl one)

Such a guess!

Yes, the curly arrow was going from the Cl-Cl to the double bond, so the arrow is in the wrong direction.
And yes the instantaneous dipole on the Cl-Cl was incorrect.