Edexcel A2 Chemistry Exams -6CH04 (14th June) and 6CH05 (22nd June) Discussion Thread

Original post by ChemIsTry_harder

Hi guys... Can anyone explain to me how can you solve this????
The answer is A btw.

@C0balt can explain it to you :smile:

!

Reply 1721

PlayerBB

17

Original post by Don Pedro K.

Lemme guess...this is from an IAL paper.

No actually, that's the hard truth :frown:

It's from June 2014/01

Reply 1722

Original post by C0balt

Thats UK 2014

Crap.

Reply 1723

Original post by PlayerBB

No actually, that's the hard truth :frown:

It's from June 2014/01

I haven't done this one yet, doing it tomorrow :s sorry!

Reply 1724

C0balt

16

Original post by ChemIsTry_harder

Hi guys... Can anyone explain to me how can you solve this????
The answer is A btw.

The gas contracted because 20cm3 of H2O was condensed down as it was at room temperature. 10 of hydrocarbon therefore produces 20cm of water. Water has 2 H atoms per molecule, so from the hydrocarbon:water ratio you know that a mole of the hydrocarbon will have 4 moles of H atoms

Reply 1725

PlayerBB

17

Original post by Don Pedro K.

I haven't done this one yet, doing it tomorrow :s sorry!

That's okay! :smile:

Reply 1726

Original post by PlayerBB

That's okay! :smile:

How was the paper overall?

Reply 1727

ChemIsTry_harder

Original post by Don Pedro K.

@C0balt can explain it to you :smile:

!

Thanks!

Original post by C0balt

The gas contracted because 20cm3 of H2O was condensed down as it was at room temperature. 10 of hydrocarbon therefore produces 20cm of water. Water has 2 H atoms per molecule, so from the hydrocarbon:water ratio you know that a mole of the hydrocarbon will have 4 moles of H atoms

thank you for the detailed explanation !!! Really appreciate it!
I've been trying to solve this for so long lol :frown:

Reply 1728

C0balt

16

Original post by ChemIsTry_harder

Thanks!

thank you for the detailed explanation !!! Really appreciate it!
I've been trying to solve this for so long lol :frown:

Np, I found it difficult initially too

Reply 1729

PlayerBB

17

Original post by Don Pedro K.

How was the paper overall?

It was generally good, some hard bits, I liked the multiple choice though!!

Those hard bits are marks that can be obtained if you think thoroughly, however, I never got what that question that I sent really mean!

Reply 1730

MacroniCheese

I really hope the paper is like the Jan 2016 IAL. Tricky but not too bad and Grade boundaries were so much lower than I expected. Just have June 2015 IAL to go, saving that for tomorrow

Reply 1731

I'm getting a little confused rounding up molar ratio...

Molar ratio
C : H : O
2.1 : 5.8 : 1
2 or 3? : 6 : 1

and another question...

When do we multiply
like eg.
C : H
0.1 : 0.2
1 : 2 and not 1 : 1?

(edited 7 years ago)

Reply 1732

Blazyy

3

Original post by ihaspotato

I'm getting a little confused rounding up molar ratio...

Molar ratio
C : H : O
2.1 : 5.8 : 1
2 or 3? : 6 : 1

and another question...

When do we multiply
like eg.
C : H
0.1 : 0.2
1 : 2 and not 1 : 1?

To calculate the ratios divide each number by the smallest number.
2.1/1 = 2.1 = 2
5.8/1 = 5.8 = 6
1/1 = 1 = 1
= C2H60

Reply 1733

Original post by Blazyy

To calculate the ratios divide each number by the smallest number.
2.1/1 = 2.1 = 2
5.8/1 = 5.8 = 6
1/1 = 1 = 1
= C2H60

2.1, 5.8, 1 are the mole ratios that I got.... dividing the moles of C/H/O with the smallest mole was the previous step that I already did to get 2.1,5.8 and 1. Now what?

Reply 1734

Blazyy

3

Original post by ihaspotato

2.1, 5.8, 1 are the mole ratios that I got.... dividing the moles of C/H/O with the smallest mole was the previous step that I already did to get 2.1,5.8 and 1. Now what?

The numbers you got equal the number of moles in the empirical formula.
They are not whole numbers, so you need to round them off to 2, 6 and 1 which gives C2H60

Reply 1735

Original post by Blazyy

The numbers you got equal the number of moles in the empirical formula.
They are not whole numbers, so you need to round them off to 2, 6 and 1 which gives C2H60

Thanks! and when do we multiply? like I have solved questions where..

C : H
0.1 : 0.2
becomes
1 : 2 <-- ?

I never really understood at what situation I am supposed to do this. :s-smilie:

(edited 7 years ago)

Reply 1736