You are Here: Home

Ocr f321 23 may 2013~official discussion thread Watch

1. Na2S2O3.5H2HO How do you work out the oxidation number of sulphur in this question Please help!
2. also how do you work out the oxidation number of nitrogen in cu(no3)2????
3. (Original post by Kitnimohabbathai)
guys help!!!!!!! question 3di from the may 2010 paper!?!! table on ionisation energies for aluminium...which ionisation energies represent removing electron from s subshell???? still have four past papers left
I know that it is 2 and 3. But dont know why SOrry
4. I just dont seem to understand the roman numeral stuff....im gonna die if it comes up
5. (Original post by Freddy-Francis)
I know that it is 2 and 3. But dont know why SOrry
lol yeah the answers say either 2 and 3 or 10 and 11 but why??!?!?!
6. (Original post by Freddy-Francis)
Same
The roman numerals are simply the oxidation number of any element in the compound that can have varying oxidation numbers/ is not fixed such as oxygen or metals such as magnesium.
7. (Original post by Kitnimohabbathai)
also how do you work out the oxidation number of nitrogen in cu(no3)2????
Cu(NO3)2
Take Brackets out

CuN2O6
Now do it.
So O = -12
Cu = +2
Therefore N = 5
8. (Original post by Geronimo!)
are you sure its 5H2H0? and not 5H20?
9. (Original post by Sara_A)
I just dont seem to understand the roman numeral stuff....im gonna die if it comes up
If you give me an example of a question you don't understand i could help?
10. how do you know copper is +2?
11. hey guys can someone please post the january 2013 paper and markscheme?
12. Whose feeling prepared for this exam? I'm aiming for about 55+ in this one

Posted from TSR Mobile
13. (Original post by Kitnimohabbathai)
are you sure its 5H2H0? and not 5H20?
Na2S2O3

O = -2 -2 -2 = -6
Na = +1 +1 = +2
Therefore S = +2 +2

Sulphur = +2
14. (Original post by Kitnimohabbathai)
how do you know copper is +2?
Good question. I read it somewhere :P
15. (Original post by aa05)
hey guys can someone please post the january 2013 paper and markscheme?
Check back on page 2 or 8 i think. There is Markscheme and Question paper
16. Right time to start past papers :P
17. I managed to get a copy of the biology paper on tuesday, hopefully I'll get my hands on this chemistry paper tomorrow
18. (Original post by Freddy-Francis)
Check back on page 2 or 8 i think. There is Markscheme and Question paper
i can't find it on page 2 and there's no page 8 :P
do you mind posting it
19. (Original post by Kitnimohabbathai)
also how do you work out the oxidation number of nitrogen in cu(no3)2????

(Original post by Freddy-Francis)
Cu = +2
Nitrogen is in the 5th group and so forms a 5+ ion. Copper has a variable oxidation state (along with the other transition metals) so don't rely on it always being 2+
• (Original post by Kitnimohabbathai)
are you sure its 5H2H0? and not 5H20?

its Na2S2O3 . 5H2O

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: December 4, 2013
Today on TSR

Can it be done?

Give feedback to Cambridge here

Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

Can you help? Study Help unanswered threadsStudy help rules and posting guidelines

Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• 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