ocr a f325 revision thread

Original post by MathsNerd1

I'm sure you needed to know them for the first part of that question which asked you to explain why there wasn't a colour change or you didn't know when the thing changed, etc and wasn't this because the V2+ state is violet in colour which is similar to Mn in the 7+ state.

ohh I think I guessed that and got lucky :lol:

ocr better not do this -_- i'll be furious if we get anything not on the spec
although i think theres something about colour change with redox titrations-have a look to double check :smile:

Reply 1444

Original post by otrivine

But that is not fair, as our teacher and syllabus did not say we should learn the colour for vanadium, or titanium, only we had to know about the iron,cobalt e.t.c :mad:

ill confirm with my teacher tomorrow :smile:

there are some coloru change tests on a page somewhere in redox titrations
if not, then ocr are being unreasonable and I shall be getting revenge if we get a paper thats not fair -_-

Reply 1445

Original post by otrivine

But that is not fair, as our teacher and syllabus did not say we should learn the colour for vanadium, or titanium, only we had to know about the iron,cobalt e.t.c :mad:

I just learn it all so they can't catch me off guard at all, they still do though :-/

Reply 1446

master y

12

Original post by otrivine

But that is not fair, as our teacher and syllabus did not say we should learn the colour for vanadium, or titanium, only we had to know about the iron,cobalt e.t.c :mad:

Original post by MedMed12

ohh I think I guessed that and got lucky :lol:

ocr better not do this -_- i'll be furious if we get anything not on the spec
although i think theres something about colour change with redox titrations-have a look to double check :smile:

we do NOT need to learn the colours, the violet colour was mentioned in the question for the Vn+ thingy.

Reply 1447

Original post by MedMed12

ohh I think I guessed that and got lucky :lol:

ocr better not do this -_- i'll be furious if we get anything not on the spec
although i think theres something about colour change with redox titrations-have a look to double check :smile:

Well you are a lucky one then and you could figure it out by the information but I'd rather just know the colours so it doesn't take any time to work it out :tongue:

Lets nail this exam! I'll try to anyway

Reply 1448

Original post by master y

we do NOT need to learn the colours, the violet colour was mentioned in the question for the Vn+ thingy.

phewww thought so :P

they can't bring up something which isnt taught! i need to relearn the colour tests lol

Reply 1449

otrivine

14

Original post by MathsNerd1

I just learn it all so they can't catch me off guard at all, they still do though :-/

Agree, might as well memorise the colours then regret later :smile:

Reply 1450

Original post by MedMed12

phewww thought so :P

they can't bring up something which isnt taught! i need to relearn the colour tests lol

What are the colour tests exactly? And I thought they could as an application question as an A* standard?

Reply 1451

Original post by otrivine

Agree, might as well memorise the colours then regret later :smile:

Yeah that's how I see it really :tongue:

Reply 1452

Pride

Original post by bluedate

Examples you might need to know:

Fe^2+ (aq) + 2OH- (aq) ------> Fe(OH)2 (s)
green ------> green precipitate

Co^2+ (aq) + 2OH- (aq) ------> Co(OH)2 (s)
pink ------> light blue ppt

Fe^3+ (aq) + 3OH- (aq) --------> Fe(OH)3 (s)
yellow -------> brown ppt

Cu^2+ (aq) + 2OH- (aq) -------> Cu(OH)2 (s)
light blue -------> dark blue ppt

:biggrin:

Ok, I'm not sure why you've sent me those... Those aren't salts?

Reply 1453

Original post by MathsNerd1

What are the colour tests exactly? And I thought they could as an application question as an A* standard?

but it still has too be on the spec -_- that would be pure evil if its not, but i wouldnt doubt it..probs will but theres only soo much one can know?! theres 1000s of related things out there that are not on own spec but are related
like the purple to colourless to pale pink for one
starch one

Reply 1454

Original post by MedMed12

but it still has too be on the spec -_- that would be pure evil if its not, but i wouldnt doubt it..probs will but theres only soo much one can know?! theres 1000s of related things out there that are not on own spec but are related
like the purple to colourless to pale pink for one
starch one

Surely they're both straightforward and in the book as an example so you've just got to learn it a certain way and you'll be fine? The hardest parts for me are the electrode parts, not the calculations just the explanation parts.

Reply 1455

Better

8

Original post by Funtry

Can you link me to the paper, I can't seem to find it on the OCR website! Italicised and spoilered the 2 I can answer, can't see the third one.

Found it! Here you go bro:

http://www.ocr.org.uk/Images/81033-unit-f325-equilibria-energetics-and-elements-specimen.pdf

Any help on The molar question would be great; thanks so much.

I am still not sure I understand that Rate of Formation. Does that mean if they asked for the rate of formation of Methenal then is would be (Rate)x4

Do you always have to put the Ratios in terms of integers?

Side Note: MasterY - Wow your school made you sit 3 mock papers for Chem 4. That is absolutely insane.

Reply 1456

bluedate

Original post by Pride

Ok, I'm not sure why you've sent me those... Those aren't salts?

They are precipitate reactions... don't know why I sent them, but they're useful I guess :tongue:

Reply 1457

Better

8

Original post by MedMed12

hey,
make sure you revise chem 4 before doing past papers, the recent spec theres only 5 or 6, so do the old spec and dont do them too early or youll get bored/nothing left.
hate chem4 -_- now that we've done chem5

Thank you for the tip! All help is appreciated for Chem 4 :O

Reply 1458