x Turn on thread page Beta
 You are Here: Home

# AS Chemistry- helping each other out! watch

1. (Original post by Super199)
Can someone help me with 1a and b?

Is 1a barium? Can someone explain it to me.

Thanks
It's barium sulphate

It's a white precipitate

Ba2+ (aq) + SO42- (aq) -------> BaSO4 (s)

Posted from TSR Mobile
It's barium sulphate

It's a white precipitate

Ba2+ (aq) + SO42- (aq) -------> BaSO4 (s)

Posted from TSR Mobile
Isn't it just barium? But I don't get why it is. Isn't barium quite vigorous when it comes to water so surely it won't just fizz.

What's part b?
3. I'm doing AQA.
4. Hi I'm on AQA AS and finished unit 1 and 2, feel free to ask any questions (PM me)
5. Could anyone taking AQA chemistry AS help shed some light onto the practicals we will likely be doing?

I'm self-teaching and all the written stuff is fine, but I've only practised titrations so slightly concerned about the practical element!
6. (Original post by haemo)
You're right, X is just barium.

The reaction with water is: Ba + 2H2O -> Ba(OH)2 + H2

The other reaction is: BaCl2 + Na2SO4 -> BaSO4 + 2NaCl
(this is what I believe the above poster meant)
7. Yo guys I desperately need help with a gas calculation:

Show by calculation that the expected volume of CO2 is greater than the 64cm3 obtained.
Assume that 1 mol of CO2 occupies 24.0dm3

This is only part of a bigger Q about the reaction of H2SO4 and MgCO3, the number of moles of H2SO4 is 0.005 and the number of moles of MgCO3 is 0.00356.

I assumed from the info given I needed to use the moles = Volume/24dm3 equation, and I thought that I would substitute in 0.00356 for the number of moles because there's a 1:1 ratio and MgCO3 is the limiting reagent.... but the answer is wrong? I got 96cm3 and the answer is 71.4cm3, suggesting that the correct number of moles of CO2 is 0.002975.

I'm guessing I'm missing a really obvious way to get the number of moles of CO2? Its driving me insane!!!!!!

Thank you
8. Anyone who does OCR Salters B done the coursework yet?

Posted from TSR Mobile
9. (Original post by Golden hawk)
The answer on that isa is wrong, it should be 0.00356 times 24000 and this should give 85.44cm3
You're joking?!? Oh my gosh I spent so long wondering what was wrong with me! Thank you
10. (Original post by Georgiam247)
You're joking?!? Oh my gosh I spent so long wondering what was wrong with me! Thank you
Don't worry I spent ages trying to figure out what I was doing wrong also, so I showed the teacher and she said that the markscheme was wrong all along.
11. (Original post by Golden hawk)
Don't worry I spent ages trying to figure out what I was doing wrong also, so I showed the teacher and she said that the markscheme was wrong all along.

That's so annoying! Was that the only wrong answer? I might as well not bother marking the rest if there's more
12. Hey guys,

I was just wondering for those on the Edexcel board for chemistry whether you have done the double-salt preparation for an assessed practical?

Thanks guys
13. AQA chemistry

Any easy way to remember Halogen equations for unit 2??
14. (Original post by Georgiam247)
That's so annoying! Was that the only wrong answer? I might as well not bother marking the rest if there's more
15. Hey guys, does anyone have the Edexcel GCE AS Chemistry specification that's explained in detail for each point? Unit 1 and unit 2 please
16. (Original post by Anne james)
Hey guys, does anyone have the Edexcel GCE AS Chemistry specification that's explained in detail for each point? Unit 1 and unit 2 please
Hey, I'm not doing edexcel but i'd imagine you can get the spec on the website right?
17. Hi everyone,

I have to do some questions about a double-salt preparation that we did and was wondering if someone could help me with a few of the questions. Rep will be given to anyone that helps.

Method:

Make one of the salts
Make the other salt
Mix them together
Boil some of the liquid off
Leave to crystallize

Firstly, why is the volume of the solution reduced? i.e. why is some of the liquid boiled off?

Also, when we were making one of the salts (ammonium sulfate solution) why did I have to keep on adding ammonia until red litmus turned red?

Finally, when calculating moles, do you include the water of crystallization in your calculations?

Thanks guys!
18. (Original post by johnjames9)
Hi everyone,

I have to do some questions about a double-salt preparation that we did and was wondering if someone could help me with a few of the questions. Rep will be given to anyone that helps.

Method:

Make one of the salts
Make the other salt
Mix them together
Boil some of the liquid off
Leave to crystallize

Firstly, why is the volume of the solution reduced? i.e. why is some of the liquid boiled off?

Also, when we were making one of the salts (ammonium sulfate solution) why did I have to keep on adding ammonia until red litmus turned red?

Finally, when calculating moles, do you include the water of crystallization in your calculations?

Thanks guys!
1) to make it as saturated as possible: crystallisation occurs when a solution is saturated so when sufficient water has evaporated, by heating you get some of that done!

2) you mean red-> blue? To ensure ammonia is in excess and so all surface (practically) had reacted.

3) very much depends on context. To calc moles of a crystalline solid you weigh? Yes include in Mr value.
19. Hi, just came across this forum - I have a qualitative tomorrow on investigating reactions with lead ... any advice or has any one has already done it?
20. Hey guys,

I was wondering, does anyone have a tutor for chemistry? I don't have any particular areas that I suck at but my teacher is so careless I feel like it'd be a good idea to get one. Anybody seen a lot of benefit from a tutor?

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: July 24, 2017
Today on TSR

### Been caught plagiarising...

...for the 2nd time this year

### Mum says she'll curse me if I don't go to uni

Discussions on TSR

• Latest
Poll
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE