OCR Chemistry A 2017 Exam Thread (New A Level)

How to determine the order w.r.t. H2, when we do not have fixed values for ICl?

xD

Same... I have 3 exams this week and feel behind for them all, this is my stronger Chemistry exam so I am feeling the pressure to do well

Well go tell that to my physics and chemistry teachers then

Consider yourself lucky... I got 4 this week and 2 of them are M1 and Physics...

As for being under pressure, looking at some kittens before the exam might help

xD What are they saying?
I believe that there are 2 factors into play here
1. The difference between absolute and percentage uncertainty.
2. Burettes can be scaled differently.

I'm stuck on the question below:


Which reaction is not used to make a Hess cycle for the following reaction?

C₂H₄(g) + H₂O(l) ⇌ C₂H₅OH(l)

A - ∆_fH ethanol
B - ∆_cH ethene
C - ∆_cH hydrogen
D - ∆_fH ethene

Mark-scheme: ∆_fH ethanol – ∆_fH ethane – ∆_cH hydrogen = ∆_rH so B is the correct answer
I have some difficulty understanding Hess' cycles. Can someone please explain the answer.

Thanks

afaik absolute uncertainty has only been taught on physics, so percentage is half the smallest measurement over your result?

Work out the other orders, work out their changes and then the theoretical effect on the rate. Then look at what the H2 is doing and whether or not that has an additional effect on rate.
Do you want me to have a go or is this enough? Hope this helps!

Oh that's simple! Thank you for quick reply!

I have physical chemistry, D1 and Paper 1 Physics this week
Next week is C3, C4, physics Paper 2 and synthesis and analysis

I do I really do, anything but M1 You poor individual

awwwwwwwwwww <3

i got that question wrong too on the sample paper, i think its just using the basic knowledge of nitrogen has one lone pair and 3 bond pairs so is a triagonal pyramidal shaped so 107. I think we just started over thinking lol. how did you find biology?

Heyy CheeseIsVeg long time no see. Were you off TSR for some time? 😊

Omg that's brutal Chemistry and Physics in the same week twice. I don't know how I would've dealt with that if I continued Physics from AS. Hope you'll be prepared enough for the exams tho.

aww you are wonderful.. which exams do you have this week if you dont mind me asking

Anyone?

Mr Vincz!!! I was Did you miss me? xD

I'm dying if that answers your question


No, you!
I have physical chemistry tomorrow, D1 the morning after and Paper 1 Physics the morning after that :O
Please accept this cat and duck image after that gorgeous kitten



To be honest, I haven't a clue

Mr Vincz!!! I was Did you miss me? xD

I'm dying if that answers your question


No, you!
I have physical chemistry tomorrow, D1 the morning after and Paper 1 Physics the morning after that :O
Please accept this cat and duck image after that gorgeous kitten



To be honest, I haven't a clue

Of course. It felt like something was missing on TSR .

Yeah it's an answer. Aww cheer up!

Awww that is so cute! I'm in love ... What are their names?

And are you doing AQA for physics?

Awh I'm sure it didn't but that's sweet of you to say

xD ah I will come July

I'm really stuck on this buffers question.

What equation do I need to make to find the equilibrium concentrations of HA and A- ?

I got HA as 0.5 and A- as 1.25 when A- is meant to be 1.5

2C2H5COOH + Mg ------ (C2H5COO)2 Mg + H2