You are Here: Home

Aqa chem 4/ chem 5 june 2016 thread Watch

1. Thank u both!! I get it now
(Original post by Parallex)
You can either use both moles or both concentrations. This works because the number of moles = concentration/volume, so the factor of 1/v cancels on each side of the fraction.
(Original post by SirRaza97)
2d(i) You can use the concentration but that would take much longer to do but should give the same answer. You would fond the conc of each in the total volume and use that. Using mol values negates the fact that they are in equal volume so it's much easier.

2d(ii) Adding OH- will get rid of H+ ions. So equilibrium will shift to the right to make up for the loss of H+ thus more of the acid will dissociate. So the amount of HA decreases and the amount of Y- increases. Again the conc of each can be calculated but it would take longer to do.

HA mol - mol of OH added and NaY mol + mol of OH added.
2. (Original post by Superbubbles)
why is it at half neutralisation point that there are equal moles of HA and A-?

Hopefully that's alright for you.
3. how do you know when to use amino and amine when naming a compound.?

And when they say to write the equation blah blah. Is the equation always in this format : CH3CH2 or do we use molecular formula? .... ( idk if this makes sense)
4. (Original post by Thisshouldbeapun)
What are the conditions for the use of NaBH4 as a reducing agent to reduce aldehydes and ketones?
i stick with LiAlH4 and condition is ether
5. What's the rule for naming a compound and putting in the e and when you don't put the e in? For example hexanedioic acid. When would I not put the e in?
6. (Original post by Lilly1234567890)
how do you know when to use amino and amine when naming a compound.?

And when they say to write the equation blah blah. Is the equation always in this format : CH3CH2 or do we use molecular formula? .... ( idk if this makes sense)
amino is when there is an acid group and amine group. Amine is when there is only amine group. Amide is when there is amine group and carbonyl group.

You can write the molecular formula if you want. I suggest that you stick with the structural one though (makes it easier to see what is replacing what in the molecule)
7. (Original post by SirRaza97)
What's the rule for naming a compound and putting in the e and when you don't put the e in? For example hexanedioic acid. When would I not put the e in?
Im not sure if this is the "official" rule but i've noticed that when it is singular you leave out the e, but when it is dioc/dione/diol you use the e
8. What would the structure look like if glycine reacted with an excess of bromoethane??
9. (Original post by SirRaza97)
What's the rule for naming a compound and putting in the e and when you don't put the e in? For example hexanedioic acid. When would I not put the e in?
I believe that two vowels remove the e. Other than that the e remains. Hope this helps

Posted from TSR Mobile
10. ****k this exam
11. Why do you not take excess moles in this?
12. (Original post by SirRaza97)
What's the rule for naming a compound and putting in the e and when you don't put the e in? For example hexanedioic acid. When would I not put the e in?
When the suffix begins with a vowel, you remove the e. E.g. -ol

When the suffix begins with a consonant, you keep the e. E.g. -dione

13. (Original post by dnan)
Why do you not take excess moles in this?
Never mind it's because there isn't OH- added but salt
14. http://filestore.aqa.org.uk/subjects...4-QP-JAN12.PDF
Can someone explain 6biii
Mark scheme
http://filestore.aqa.org.uk/subjects...W-MS-JAN12.PDF

15. if you go back a few pages, I explain this, take a look if it's any help!
16. (Original post by ravichauhan11)
i stick with LiAlH4 and condition is ether
thanks
17. What do we need to know about chromatography?
18. Likelyhood of a chromatography question coming up tomorrow?
19. (Original post by Mriffin)
Likelyhood of a chromatography question coming up tomorrow?
(Original post by emma_1111)
What do we need to know about chromatography?
Very likely it comes up, not likely that it is over 5 marks worth on it.

Mobile phase, Stationary phase, what the solvent does, why is it used. How it distinguishes. Different types.
20. Quite likely i'd say

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: August 27, 2016
Today on TSR

Last-minute PS help

100s of personal statements examples here

More pressure for kinky sex?

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

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.