A-level Chemistry Study Group 2020-21

Reply 760

SapphirePhoenix1

16

Original post by Hellllpppp

I don’t know this was all that was released

OH ok
(I haven't actually looked at the assessment materials lol)

Reply 761

Hellllpppp

20

Original post by Cherrypop13

yes thats the one i don't know if i'm doing it correctly i got 7.2 x10-3

Just be careful as it says 3sf so it’s got to be 7.21 :biggrin:

(edited 2 years ago)

Reply 762

Cherrypop13

6

Original post by Hellllpppp

Just be careful as it says 3sf so it’s got to be 7.21 :biggrin:

ah yes thank you guys :smile:

Reply 763

idk__21

13

does anyone know the answers for these ?

(edited 2 years ago)

Reply 764

Hellllpppp

20

Original post by idk__21

does anyone know the answers for these ?

19 - work out moles of buta-1,3-diene and use the 1:1 ratio and mol/concentration = volume, then convert dm3 -> cm3

10 - convert mg->g->mol and convert cm3->dm3

Reply 765

idk__21

13

Original post by Hellllpppp

19 - work out moles of buta-1,3-diene and use the 1:1 ratio and mol/concentration = volume, then convert dm3 -> cm3

10 - convert mg->g->mol and convert cm3->dm3

thank you

Reply 766

bananas44

8

Does anyone know how to do this question? The answer is D but idk how to get there, TIA

One mole of which of the following chlorides would have the greatest entropy at 750 °C?
A) Sodium chloride
B) Calcium chloride
C) Potassium chloride
D) Magnesium chloride

Reply 767

sumayaaa

15

hey guys

what chem youtubers do you guys recommend? I do OCR A. I know about allery chemistry and he’s been good. I need a youtuber good at organic chem bc i need to catch up/learn about that

thanksss

Original post by sumayaaa

hey guys

what chem youtubers do you guys recommend? I do OCR A. I know about allery chemistry and he’s been good. I need a youtuber good at organic chem bc i need to catch up/learn about that

thanksss

MaChemGuy

Reply 769

sumayaaa

15

Original post by CaptainDuckie

MaChemGuy

will check him out rn to prepare for tomorrow’s lesson, thanksss

Original post by sumayaaa

will check him out rn to prepare for tomorrow’s lesson, thanksss

Preferably both old and new videos are good, but I think the white board style videos are more interactive, feels as though he’s teaching you IRL.

Reply 771

sumayaaa

15

Original post by CaptainDuckie

Preferably both old and new videos are good, but I think the white board style videos are more interactive, feels as though he’s teaching you IRL.

oh okay, yeah i think i prefer those videos.
does he just do OCR A?

Original post by sumayaaa

oh okay, yeah i think i prefer those videos.
does he just do OCR A?

Yeah, only OCR A videos. He tries to explain each step too, overall I’d give it 10/10 imo.

Makes tough concepts much easier to understand.

Original post by bananas44

Does anyone know how to do this question? The answer is D but idk how to get there, TIA

One mole of which of the following chlorides would have the greatest entropy at 750 °C?
A) Sodium chloride
B) Calcium chloride
C) Potassium chloride
D) Magnesium chloride

I would think that the answer is B rather than D

Reply 774

hiiiiiiiiiiii2

16

Original post by charco

I would think that the answer is B rather than D

the positive ion should be the smallest and highest charge, and the negative ion should be large and highly charge so it should be D

Original post by hiiiiiiiiiiii2

the positive ion should be the smallest and highest charge, and the negative ion should be large and highly charge so it should be D

The magnitude of absolute entropy in ionic compounds depends on the relative strength of the ionic attraction. Weaker = more entropy

Actual values:
MgCl₂: 89.62 J K^-1 mol^-1
CaCl₂: 104.62 J K^-1 mol^-1
[ref: https://webbook.nist.gov/cgi/cbook.cgi?ID=C10043524&Mask=2]

Reply 776

bananas44

8

Original post by charco

I would think that the answer is B rather than D

Marking scheme says D

EDEXEL gang

What exam board are you taking?
Edexel
What's your favourite topic in the course so far?
Kinetics
And your least favourite topic?
Reaction mechanisms
What are you hoping to study at university?
Medicine