You are Here: Home

# Edexcel Chemistry IGCSE 1C Unofficial Mark Scheme 19th May 2016 Watch

• View Poll Results: How did you find this exam?
Very easy
13.97%
Easy
28.19%
Okay
43.87%
Hard
10.78%
Very hard
3.19%

1. Thank you for helping!
1. No, it asked for a compound.
2. It is CaCO3.
2. (Original post by MMay2000)
that makes no sense?
It does, the acid is in excess in both experiment 1 and 2 so the magnesium is all reacting in both. The magnesium is giving a 'set amount of energy' out and this means that in the second experiment, it is having to heat up twice the amount of volume of acid as before with the same energy. Therefore the rise in temperature is less. If you topped up a bath or a swimming pool with a kettle, same amount of heat energy in the kettle, but the temperature of bath is obviously going to increase more.
3. I think the empirical formula qu. has been missed out?? Sorry, cant remember which question is was...
4. (Original post by deardood)
It does, the acid is in excess in both experiment 1 and 2 so the magnesium is all reacting in both. The magnesium is giving a 'set amount of energy' out and this means that in the second experiment, it is having to heat up twice the amount of volume of acid as before with the same energy. Therefore the rise in temperature is less. If you topped up a bath or a swimming pool with a kettle, same amount of heat energy in the kettle, but the temperature of bath is obviously going to increase more.
Thank you omg so many people didn't get it.
I already went through this. They doubled to volume of acid used, so even though its already in excess, because the reaction will give of the same amount of energy, because the volume has doubled, it requires more energy for the same increase in temperature, so the rise in temperature is less.
I'm sure the wording of the question was as follows: "The experiment is repeated again, this time using a volume of 50cm3 of dilute acid, describe the diffrence in temperature"

If this is indeed the wording, then the anwser will be no change, and the acid is in excess, and therefore the reaction completes at the same rate and thus temperature. Your argument that there is more acid to heat is fair, but unfortunately as it asks for the temperature of the reaction, I'm sorry to say it is incorrect.
6. (Original post by Togarty12)
I'm sure the wording of the question was as follows: "The experiment is repeated again, this time using a volume of 50cm3 of dilute acid, describe the diffrence in temperature"

If this is indeed the wording, then the anwser will be no change, and the acid is in excess, and therefore the reaction completes at the same rate and thus temperature. Your argument that there is more acid to heat is fair, but unfortunately as it asks for the temperature of the reaction, I'm sorry to say it is incorrect.
Yes, but it doesn't reach the same temperature because it has to heat twice as much acid?
7. (Original post by deardood)
Yes, but it doesn't reach the same temperature because it has to heat twice as much acid?
As stated in my post, the question asked for the temperature of the reaction, not the temperature of the acid after the reaction. If you heat up a pool of water at the centre, and we go by your theory, then the water furthest from the pool should be as hot as that next to the heat source? That's not how water works, it's in a beaker and so is not flowing. The same ammount of acid comes into contact with the metal in experiment 1 as in experiment 2.
8. (Original post by Togarty12)
I'm sure the wording of the question was as follows: "The experiment is repeated again, this time using a volume of 50cm3 of dilute acid, describe the diffrence in temperature"

If this is indeed the wording, then the anwser will be no change, and the acid is in excess, and therefore the reaction completes at the same rate and thus temperature. Your argument that there is more acid to heat is fair, but unfortunately as it asks for the temperature of the reaction, I'm sorry to say it is incorrect.
You are wrong it doesn't matter if it's in excess or not. The fact is that the same heat is generated but this heat has to be transferred through a larger volume of liquid so the overall temperature will be less as the heat will have to be shared out through more particles of solution.
9. my thinking behind that question was to do with concentration, - does doubling the volume of acid decrease its concentration- so less collisions per second etc and lower rate of reaction? not completely sure
10. whats the answer to the one about the mass of water produced with the 5H20
when it said the mass of one side is 2.50 grams
11. Answer to calculating mass in reactions, "0.9"?!
12. (Original post by HKHASSAN)
Im pretty sure it is CH2
I agree with Pedaly7, it was a double bond so CH2 couldn't possible exist
13. (Original post by Gdmn)
You are wrong it doesn't matter if it's in excess or not. The fact is that the same heat is generated but this heat has to be transferred through a larger volume of liquid so the overall temperature will be less as the heat will have to be shared out through more particles of solution.
The reason I base my argument as on doing a past paper last night, this exact question came up. http://qualifications.pearson.com/co...e_20140114.pdf

See Q10 which is almost identical to today. Then look at the mark scheme for that question!

http://qualifications.pearson.com/co...c_20140306.pdf
14. (Original post by Gdmn)
You are wrong it doesn't matter if it's in excess or not. The fact is that the same heat is generated but this heat has to be transferred through a larger volume of liquid so the overall temperature will be less as the heat will have to be shared out through more particles of solution.

I thought it wasn't the heat of the acid? it's the heat given off/temperature change.
15. (Original post by Robertarthur)
I agree with Pedaly7, it was a double bond so CH2 couldn't possible exist
it does
16. (Original post by MMay2000)
I thought it wasn't the heat of the acid? it's the heat given off/temperature change.
The heat given off is the temperature of the acid
17. (Original post by Robertarthur)
I agree with Pedaly7, it was a double bond so CH2 couldn't possible exist
Doesn't matter whether it can 'exist' or not, the empirical formula is the simplest ratio of atoms therefore the empirical formula of Propene is CH2

Posted from TSR Mobile
18. (Original post by Robertarthur)
I agree with Pedaly7, it was a double bond so CH2 couldn't possible exist
It doesn't matter where it exists or not, it's the empirical formula - the lowest ratio - regardless
19. (Original post by Togarty12)
I'm sure the wording of the question was as follows: "The experiment is repeated again, this time using a volume of 50cm3 of dilute acid, describe the diffrence in temperature"

If this is indeed the wording, then the anwser will be no change, and the acid is in excess, and therefore the reaction completes at the same rate and thus temperature. Your argument that there is more acid to heat is fair, but unfortunately as it asks for the temperature of the reaction, I'm sorry to say it is incorrect.
Yeah its asking for the difference in temperature of the acid, because thats whats being measured. If the same amount of energy is being release and is transferred to the acid of a higher volume, the average kinetic energy of the particles will be less overall due to having more particles.

Anyway, its all up for debate now, however, the outcome will be the outcome.
Yeah I can't think of them and I've done this mark scheme for so long I'm just tired right now.
I understand you're tired but perhaps later on in the night you could update it. I really appreciate what you're doing as I was really doubtful of my answers and this unofficial mark scheme reassures me thus relieving stress. Thank you

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 11, 2016
Today on TSR

### How to stand out in an Oxbridge interview

What makes you memorable?

### A pregnant woman visits me every night

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