Jan 10 Q1:

Increasing pressure shifts eql. to the right yes? So more PCl5 is formed.

Mole fractions are just the percentage/ratio that one molecule is representing out of the total, so if more PCl5 is formed: less moles of Cl2 + PCl3 are left. So now the moles of PCl5 are taking a bigger chunk of the total moles (Cl2 + PCl3 + PCl5). Does that make any sense?

Yes thank you! What about Q3 in that paper? How do you know that?

Reply 768

MeeraP07

7

Guys, just wanna check, the exams in the morning right? Haha

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(edited 8 years ago)

Reply 769

MeeraP07

7

Original post by Undisclosed 15

It's exactly the same syllabus so they're not taught differently

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The R papers are the ones we would sit if ours was leaked or went missing or something (I think) so deff worth doing them

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Reply 770

rasil23

3

Original post by MeeraP07

Guys, just wanna check, the exams in the morning right? Haha

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Afternoon

Reply 771

HopefulDentist..

2

Original post by MeeraP07

Guys, just wanna check, the exams in the morning right? Haha

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nooooo afternoon, you scared me

Reply 772

MeeraP07

7

Original post by rasil23

Afternoon

Hahah omg thank you!

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Reply 773

MeeraP07

7

Original post by MeeraP07

Hahah omg thank you!

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Haha so sorry!

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Reply 774

Nautic4l

12

Anyone know how to read the entropy values in the data book? It's confusing

Standard molar entropy at 298 K says in brackets/: the values of standard entropy of diatomic gaseous elements is for 1/2 mol of the element) so is the value only 1/2 mol for CO2?

Reply 775

Wahid1

7

Original post by Wahid1

In that link why can't you simply use equilibrium moles for example three?
2 moles of products and reactants...

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Anyone?

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Reply 776

Wahid1

7

Original post by Wahid1

All we need to know about hplc and glc is basically that 6 marker that came up once right?

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Confirmation required

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Reply 777

Hairysweets

3

Original post by Nautic4l

Anyone know how to read the entropy values in the data book? It's confusing

Standard molar entropy at 298 K says in brackets/: the values of standard entropy of diatomic gaseous elements is for 1/2 mol of the element) so is the value only 1/2 mol for CO2?

The value for anything diatomic is only the entropy per atom, so if you needed N2 for example you'd double the value but not for a compound.

And Q3:

Indicators are in the eql:
HIn <-> In- + H+
(Colour A) (Colour B)

So adding OH- removes H+ shifting it to the right, forming more In- (Colour B). Negative ion = Anion

Reply 778

rowanbarnesss

2

Original post by Nautic4l

Anyone know how to read the entropy values in the data book? It's confusing

Standard molar entropy at 298 K says in brackets/: the values of standard entropy of diatomic gaseous elements is for 1/2 mol of the element) so is the value only 1/2 mol for CO2?

CO2 isn't diatomic!

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Reply 779

lizzie97

3

Can someone please do this question and go through it step by step, preferably taking a photo of your method please? im so confused
An experiment was carried out to determine the value of Kc for this reaction.
0.120 mol of ethanoic acid was added to 0.220 mol of ethanol.
5.00 cm3 of 1.00 mol dm–3 hydrochloric acid was added as a catalyst. Thiscontains 0.278 mol of water.
The mixture was left to reach equilibrium.
The mixture was titrated with 1.00 mol dm–3 sodium hydroxide, whichreacted with both of the acids.
The titre was 45.0 cm3. Use these data to determine the value for Kc.

Edexcel A2 Chemistry 6ch04/05 JUNE 2015

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