x Turn on thread page Beta
 You are Here: Home

# ocr a f325 revision thread watch

1. (Original post by Better)
January 2013 might have been the hardest thing I've ever done in my life. I had no clue what to do for Question 8. If they make another dumb paper like that one, I will literally fight someone.
I remember doing that as my mock paper in class, it was a beast of a paper and if we got anything similar to that then I think I would just walk out during the exam! I feel it's quite able to get at least 70/100 though which would've been an A if I remember correctly.

What did you get in this?

Posted from TSR Mobile
2. (Original post by CCLK)
Hey Guys I just cracked redox titrations I was feeling the same helplessness and stress as you guys but now I love them. Personally I recommend everyone struggling with them to sit down with your teacher, personal tutor or even anyone you know who can help. What really helped me was going through it with someone step by step. I can't stress this enough. DRAW A DIAGRAMMATIC picture of whats going on EXACTLY. If the stem says ' 25cm^3 of solution was taken from the original sample of 250cm^3' DRAW IT IN YOUR diagram like an equation of whats going to what on a seperate sheet of paper show yourself that its been divided by ten so that when you get your moles you know to times it by ten to get you moles in 250 etc. I can't stress it enough about how important it is that you make it clear what the student in the question is doing. Once you do this it becomes so much easier. http://www.chemteam.info/Redox/WS-re...-problems.html This site also has some really good questions which I feel were challenging enough to warm you up for exam questions. Hope this helps. AND GOING THROUGH IT WITH SOMEONE WHO KNOWS EXACTLY WHATS GOING ON IS EQUALLY IMPORTANT. I feel it's something that needs to be taught to you in great detail.

Now I have a problem myself. If anyone can show me some good note of what goes on in lattice enthalpy of hydration & solution questions I'd really appreciate it. I Just don't understand the concepts of why a metal higher then another in the group of the periodic table would have a higher lattice enthalpy of hydration. I thought it'd be the other way round. (This paragraph is probably is wrong in terms of the chemistry of it which shows how confused I am by the concepts).
Depends on the context of the question but I believe my Teacher said something about the Lattice Entalpy is more significant because it is more Exorthermic (more negative/ -ve). HENCE when you draw out the Diagram this ends up resulting in a high value for the Enthalpy of Hydration (more positive/ +ve )

Please would anyone be able to give tips on the Redox Titrations as well. I am about to Maths and still have yet to mark my paper.

But what do you my by a Diagram?

The only things I know are these REDOX Reactions:

o MnO4- ---> Mn2+
o Cr207- ---> Cr3+
o I2/ S2032-
o I2/ Cu2+

And the Molar Equations.

I really have no clue why the Examination Questions seem so different to this?

Please can someone help I am literally freaking out.
3. (Original post by Better)
Found it bro!!

Here you go
done it! I realised halfway through that I'd done the last question before in class, only after I got the 5:3 ratio. I was worried as before I was convinced it was 2, but nonetheless, the ratio was the only thing I remembered from that q, and that was after I got it.

I've also done some of the q's before in tests etc, but I'm hoping that it doesn't sway my results too much. Might knock 4 off just for that

Gonna mark it quickly.
4. (Original post by Better)
Depends on the context of the question but I believe my Teacher said something about the Lattice Entalpy is more significant because it is more Exorthermic (more negative/ -ve). HENCE when you draw out the Diagram this ends up resulting in a high value for the Enthalpy of Hydration (more positive/ +ve )

Please would anyone be able to give tips on the Redox Titrations as well. I am about to Maths and still have yet to mark my paper.

But what do you my by a Diagram?

The only things I know are these REDOX Reactions:

o MnO4- ---> Mn2+
o Cr207- ---> Cr3+
o I2/ S2032-
o I2/ Cu2+

And the Molar Equations.

I really have no clue why the Examination Questions seem so different to this?

Please can someone help I am literally freaking out.
Don't freak out just chill you'll get it trust me. By I diagram I mean like literally drawing a picture of a beaker or whatever you want your solution to be in and labeling it for each step. So you know exactly what your working with. Even re-writing the equation but adding annotations to it to show exactly the concentrations and volumes are for one of reactants or products. Before I go into details what exactly are you having trouble with? are you like I was and just getting the wrong answer even though you thought you were going the right direction? Do you have anyone who can help you with it?
5. (Original post by Better)
Found it bro!!

Here you go
96%, I took 5 marks from that, so 91%. Wasn't too bad, some horrible questions though (like the last one) and some factual recall ones, which I always hate
6. (Original post by Funtry)
96%, I took 5 marks from that, so 91%. Wasn't too bad, some horrible questions though (like the last one) and some factual recall ones, which I always hate
how r u doing so well on these papers? whats ur secret? :P
7. (Original post by Better)
Depends on the context of the question but I believe my Teacher said something about the Lattice Entalpy is more significant because it is more Exorthermic (more negative/ -ve). HENCE when you draw out the Diagram this ends up resulting in a high value for the Enthalpy of Hydration (more positive/ +ve )

Please would anyone be able to give tips on the Redox Titrations as well. I am about to Maths and still have yet to mark my paper.

But what do you my by a Diagram?

The only things I know are these REDOX Reactions:

o MnO4- ---> Mn2+
o Cr207- ---> Cr3+
o I2/ S2032-
o I2/ Cu2+

And the Molar Equations.

I really have no clue why the Examination Questions seem so different to this?

Please can someone help I am literally freaking out.
The guy before said to draw diagrams. I thought this would be a waste of time...boy was I wrong
Honestly it is the best advice for these types of questions. You have much less chances of making a mistake and u know exactly what is going on. The equations you have listed are right for the redox titrations...but in the Jan 2013 paper the difficult was trying to come up with a redox equation
That is why they asked you to work out the charge of the V in the solution so u know what ratios they reacted in. I personally tried a different method by finding out the moles of electrons and then from that working out the molar ratios because the moles of electrons gained by Mn is exactly the same as those lost by V....just me who does it this way?

Honestly just try lots of practice questions and it gets much better, believe me man. I hated redox titrations 2 weeks ago but now I really want a question on it to come up
8. (Original post by master y)
how r u doing so well on these papers? whats ur secret? :P
Just read the question.

Seriously, it seems like such an easy thing, but if you read the question, each word, especially in titration questions. mull it over for a bit, and then write, you should get the answer. I myself, last year, would see WRITE A REDOX EQUATION or whatever,,and jump straight in, missing pieces of information that I just shouldn't have.
9. I don't know if January 2013 put me off calculations all together, I had no clue about most of them
10. (Original post by CCLK)
Don't freak out just chill you'll get it trust me. By I diagram I mean like literally drawing a picture of a beaker or whatever you want your solution to be in and labeling it for each step. So you know exactly what your working with. Even re-writing the equation but adding annotations to it to show exactly the concentrations and volumes are for one of reactants or products. Before I go into details what exactly are you having trouble with? are you like I was and just getting the wrong answer even though you thought you were going the right direction? Do you have anyone who can help you with it?
Thanks for the advice.

Please can you guys tell me what Questions would be best to do to master this, and could you give me a plan or some sort, so I get a vague idea of what you guys are doing/your thought process.

Generally I look at the question write a few things down and then I think - I haven't got enough data, or I don't know which half-equations to use for this one.

When it comes to Calculations my teacher isn't very good at explaining stuff; he just says "yes its tricky" - To which I respond -____- . Need to get this mastered by at least Thursday/Friday if I want to go into the exam confidently.

I think the rest of the syllabus is okay but its just this part makes me want to cry.
11. Just marked my Paper, here is my score Breakdown:

Total Score 77/100
Q1: 11/13
Two Elements that have atoms with two unpaired d electrons - Not so sure

Q2 - 10/11
Boom was so happy about this. The Mass is in fact the Net Mass
Forgot to put a -ve sign in front of my answer

Q3 - 15/16 - small error

Q4 5/10

Not sure about How to determine the initial rate?
I think I understand part c now.

Q5 - 7/10

ARGH, I tried to jump steps on the Equilibrium question, probably best to write things down explicitly

Q6 - 14/14

Q7 - 13/16
- Not sure about the full Ionic equation of Q7bii - Ca(HS03)2 OXIDISES Magnesium.. I think because there were two metals I was confused, could anyone explain this part?
- Got the Reaction of the Base wrong too.
- Question 7cii - Possible Equation - Got that wong apparently it was Benzoic Acid
- The last bit - I thought the rate of dissociation would be too slow so it would make a difference which apparently was wrong.

Q8- 2/10 :O :O :O
NOT sure whats going on :/ :/
12. (Original post by Lehal)
Hi there, the way I worked this out was as follows:

Step 1: Simple, combining the 2 equations given as the copper is reacting with the HNO3.. so, u just balance and combine them,
Cu(s) + 4HNO3(l) --> Cu2+(aq) + 2NO3-(aq) + 2NO2(g) + 2H20(l)

Step 2: It says that the sodium carbonate, is neutralised by any acid..
You should know that.. when acid + carbonate --> salt + CO2 + H20
So, I did.. NaCO3 + 2HN03 (as any acid, this was given so I used this- it makes no difference.. btw, u see I am writing out the equation first just to make it a bit easier to understand.. from the equation, u can then deduce the ionic equation), so NaCO3 + HN03--> Na(NO3)2 + C02 + H20

hence, ionic equation.. Na+ CO32- +2H+ + 2NO3- --> Na+ + 2NO3- + CO2 + H20

cancelling, gives.. CO32- + 2H+ --> CO2 + H20

u follow same format for equation 4, this is just how I worked it out.. try equation 4 and see if u get
Thank you for this.

I am about to go through all the Mod 3 End of Chapter Unstructured Redox Titrations and then see my teacher.

Is anybody else able to provide advice similar to this i.e. your thought process. I may just be overcomplicating things! Thanks again everyone for the support.
13. (Original post by Funtry)
96%, I took 5 marks from that, so 91%. Wasn't too bad, some horrible questions though (like the last one) and some factual recall ones, which I always hate
Bloody hell 91%!
I did it as a mock and got 84% ! which was just full UMS but still 96% is too good!
How are you revising for this?
Have yo udone all the past papers yet?
14. Looks like I will be part of this thread for the next week...need 122 at least for an A*...I need it!
15. Just been given about 20 titration questions today of which I've already completed 10 and will complete the rest and I'm beginning to struggle to see why people can't do them that well, they just need to be thought about logically and you'll be fine in the question.

Only electrode potentials and hydrogen economy to reinforce and then I'll be looking at getting a very high A* no matter what types of calculations questions or transition metal questions arise next week!!

Posted from TSR Mobile
16. (Original post by MathsNerd1)
Just been given about 20 titration questions today of which I've already completed 10 and will complete the rest and I'm beginning to struggle to see why people can't do them that well, they just need to be thought about logically and you'll be fine in the question.

Only electrode potentials and hydrogen economy to reinforce and then I'll be looking at getting a very high A* no matter what types of calculations questions or transition metal questions arise next week!!

Posted from TSR Mobile
Lol bro, you will do fantastically well if Electrode Potentials and Hydrogen Economy are your only weaknesses. Just try to visualise it and it makes it easy. I watched a 5 minute video on Youtube and it just stuck in my head. Just remembered that the only other thing you have to remember is the Transition Metals used as Catalysts.

Just a quick question:

Is there any chance you could please Upload the Titrations questions, I just did 6 from the Book, but they aren't any where near as difficult as the Exam ones.
I.e are you able to get them in an Eletronic Format?
17. (Original post by Better)
Lol bro, you will do fantastically well if Electrode Potentials and Hydrogen Economy are your only weaknesses. Just try to visualise it and it makes it easy. I watched a 5 minute video on Youtube and it just stuck in my head. Just remembered that the only other thing you have to remember is the Transition Metals used as Catalysts.

Just a quick question:

Is there any chance you could please Upload the Titrations questions, I just did 6 from the Book, but they aren't any where near as difficult as the Exam ones.
I.e are you able to get them in an Eletronic Format?
Thanks, I want flawless marks this year!!

And I wouldn't be able to as they are paper copy but I could post them in pictures for you?

Posted from TSR Mobile
18. soooooo scared
19. (Original post by Better)
...
Here are the questions, I hope they are big enough to read.

Posted from TSR Mobile
20. (Original post by MathsNerd1)
Thanks, I want flawless marks this year!!

And I wouldn't be able to as they are paper copy but I could post them in pictures for you?

Posted from TSR Mobile
If you can that would be great.

Yeah Transition metals really have me :/ and if you some of you guys are really great at these subjects, so I need all the help I can get!

I forgot to tell you my mark, I got 77/100 on the June 2013 Paper, had I not made a few silly mistakes I would have been on around 85/100 - The Transition Metals pretty much has me baffled.

If I can nail them I think I should be able to score as high as some of you - I'm pumped to master this!

Yesterady I was terrified but you guys are making me feel like I can do it

We're all gonna make it brah's !

Turn on thread page Beta
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

### Four things top students are doing

Over the Easter break

Poll
Useful resources

## Make your revision easier

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