Of course. I got a U in my first chemistry test and now I'm averaging As. Just gotta understand the content, go over it regularly and do past papers. I usually watch YouTube videos on the topics I find difficult and that helps.

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Thank your your advise will definitely do that

Reply 1768

kira1

Original post by Disney0702

Hi there!

I am an A2 Chemistry student.

I got an A last year at AS level.

In the March MOCKs I got a U grade for Chemistry but that was because I lacked understanding at that time.

To help me understand better I bought the CGP text book which helped contribute to my A grade.

I recommend you get it if you really want that high A grade.

CGP AS Chemistry

SAMPLE PAGES

I also recommend you do lots of past papers so help strengthen your exam technique.

Thank you so much
I have that book
And I will start to use it more wisely
I really appreciate your reply :smile:

Reply 1769

prophetkid

Can somebody help me please?
When testing for a sulfate ion, you add BaCl2 to form a white precipitate. If no sulfate ion is present, what is the observation? Does the solution stay clear or can a different coloured precipitate form?

Reply 1770

C0balt

Original post by prophetkid

the solution stays colourless.
All group 2 compound form white precipitate
Only transition metals form coloured ones (dichromate, permagnate have colours but they are transition metal anion)

Reply 1771

prophetkid

Original post by C0balt

the solution stays colourless.
All group 2 compound form white precipitate
Only transition metals form coloured ones (dichromate, permagnate have colours but they are transition metal anion)

Thank you! Do you know which transition metals would form a blue precipitate?

Reply 1772

C0balt

Original post by prophetkid

Thank you! Do you know which transition metals would form a blue precipitate?

Cu2+ ion is blue

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Reply 1773

Uwaiss

How do I work out;

mass of MG(OH)2 that may have been used in the medicine.

Mass = molesxmr
mass = moles x 58.3

Info given is; hcl moles is 20.4 x 10^-3
The amount of acid which was used was 50cm^3 and concentration was 1moldm^3

(may need to work the hydroxide ions or something along them lines?)

Reply 1774

samb1234

Original post by Uwaiss

Write out the balanced chemical equation for the reaction and then you can work out the mole ratio

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Reply 1775

khushboo1028

Hey!
Can you please tell me how do you do this?
It would be great help!
Thanks a lot :smile:

The answer is C btw but idk how!

Screenshot (48).png21.4KB

Reply 1776

Uwaiss

Original post by samb1234

Write out the balanced chemical equation for the reaction and then you can work out the mole ratio

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Mg(OH)2 + 2HCL -> MgCl2 + 2H20

2:1 ratio now what dude

Reply 1777

C0balt

Original post by Uwaiss

ratio 1:2 because
Mg(OH)2+2HCl -> H2O+MgCl2

So number of moles of Mg(OH)2 is half that of HCl

Multiply it by the Molar mass of Mg(OH)2 and that's the mass of Mg(OH)2

(edited 9 years ago)

Reply 1778

C0balt

Original post by C0balt

ratio 1:2 because
Mg(OH)2+2HCl -> H2O+MgCl2

So number of moles of Mg(OH)2 is half that of HCl

Multiply it by the Molar mass of Mg(OH)2 and that's the mass of Mg(OH)2

and about that ion thing, it's a separate question
if you want the number of moles of OH- ions that is double the number of moles of Mg(OH)2 because there are 2 OH- in one Mg(OH)2

Reply 1779

chemphys

Ok hi, I recently asked about carrying forward answers rounded or unrounded
can any one else doing aqa confirm that this format is acceptable

a) X/n = 2.46728478
= 2.47 (3sf)
Part b depends on part a

b) m = (2.467...)(5)
= 12.33572814684 (not actual value)
=12.3 (3sf)