You are Here: Home

# ocr a f325 revision thread Watch

1. (Original post by bmpink)
115 isn't bad! I need about 83% if I didn't go up in my F321 retake, but I genuinely have no idea how it went because it's so much easier than A2 I feel like I have nothing to gage it on! Good luck! If you need any more help ask me because I need the practice!!
Ah I see, I know what you mean.. i resat F321 in January and went from 69/90 to 86/90 it is not even comparable to what we're going to face on Wednesday is it!
Thank you I will :P
2. An unusual compound of iron has been detected on the surface of the planet Mars. This compound contains the ferrate(VI) ion.
A student uses 1.00 g of iron(III) oxide and makes, on crystallisation, 0.450 g of sodium ferrate(VI), Na2FeO4.
Calculate the percentage yield, by mass, of sodium ferrate(VI).

how did they get the mass of Sodium ferrate as 2.08g ? thanks
3. anyone here got jan 13 ms
4. (Original post by needtosucceed=))
no idea im afraid :/ in the specification it states only for monoprotic acids :/
it seems like a reasonable thing to do if it does come up
You got the first post of page 100
Lucky.
5. (Original post by bmpink)
115 isn't bad! I need about 83% if I didn't go up in my F321 retake, but I genuinely have no idea how it went because it's so much easier than A2 I feel like I have nothing to gage it on! Good luck! If you need any more help ask me because I need the practice!!
bmpink, please could you help me with a question that I have posted on the previous page (I think or page before)?
6. (Original post by otrivine)
An unusual compound of iron has been detected on the surface of the planet Mars. This compound contains the ferrate(VI) ion.
A student uses 1.00 g of iron(III) oxide and makes, on crystallisation, 0.450 g of sodium ferrate(VI), Na2FeO4.
Calculate the percentage yield, by mass, of sodium ferrate(VI).

how did they get the mass of Sodium ferrate as 2.08g ? thanks
Fe2O3 > 2NaFeO4

so you find the moles of Fe2O3, multiply by 2 for the moles of NaFeO4 then multiply by Mr for the mass
7. (Original post by otrivine)
they put 1 ?
Yes that makes sense actually. 1 mole to 1 mole. Stoichiometry is equal.
8. (Original post by F Hopeful)
Fe2O3 > 2NaFeO4

so you find the moles of Fe2O3, multiply by 2 for the moles of NaFeO4 then multiply by Mr for the mass
9. (Original post by _HabibaH_)
Yes that makes sense actually. 1 mole to 1 mole. Stoichiometry is equal.
is it because of the mole ratio
10. (Original post by otrivine)
you find the Mr of Fe in Fe2O3 which is 159.6

n(Fe2O3) = mass/mr

1/159.6= 0.006266 mol

what I did then was set up an equation for the reaction so

Fe2O3 + 4Na + 5H2O----> 2Na2FeO4 + 5H2

the ratio of Fe2O3 to Na2FeO4 is 1:2 so moles of Na2FeO4 = 2x0.006266 = 0.012532

mass of Na2FeO3= moles x mr = 0.012532x165.8= 2.08g

11. (Original post by otrivine)
is it because of the mole ratio
Yep. Is there anything you found hard cuz you know A LOT so anything you think is worth looking at, would help everyone I think.
12. (Original post by Namod)
You got the first post of page 100
Lucky.
OMG really.
i'm a don :')
13. Hey all just a small question, when drawing out complex ions in 3d form whats the best way to show it being a dative bond without it looking messy?
because i see that they sometimes dont even draw arrows showing its dative?

Cheers
14. (Original post by _HabibaH_)
Yep. Is there anything you found hard cuz you know A LOT so anything you think is worth looking at, would help everyone I think.
Sorry I just keep getting panicked when exam is getting closer
15. (Original post by otrivine)
Sorry I just keep getting panicked when exam is getting closer
Same lol. When I'm not panicking, i'm wasting time thinking of how much I'm panicking.
16. (Original post by Tidius)
Hey all just a small question, when drawing out complex ions in 3d form whats the best way to show it being a dative bond without it looking messy?
because i see that they sometimes dont even draw arrows showing its dative?

Cheers
You don't need to show it's dative, just make sure it's 3D structure is clear.

Posted from TSR Mobile
17. Quick question, do we have to cover Kp?
18. The cell represented below was set up under standard conditions.
Pt|Fe2+(aq), Fe3+(aq)||Tl3+(aq),Tl+(aq)|Pt Cell e.m.f. = + 0.48 V
(i) Deduce the standard electrode potential for the following half-reaction.
Tl3+(aq) + 2e– → Tl+(aq)
................................ ................................ ................................ ...........................

how?
19. Also when calculating entropy ^S and there are two moles of either a reactant or product as a pose to one, do we then times the number in the table by two, or not?
Resitting this paper, everything just went wrong in January
Exactly happened with me in my other exams I got an A and B comes F325 i landed myself an E was gutted

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: June 8, 2014
Today on TSR

### Living with thieves

My housemates are stealing my food

### Should I WhatsApp him?

Poll
Useful resources

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

## Groups associated with this forum:

View associated groups

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.