You are Here: Home

# Errors in enthalpy change reaction Watch

1. Why isn't 3 part of the answer because a lower mass of water means that q is lower so surely enthalpy change of combustion will also be lower since the value of q is smaller. Thanks

2. What's the whole question?

Just think about it, will the same energy heat up a smaller amount of water more or less? Q is the same as you are burning the same amount of fuel, m is just smaller than you think.
3. (Original post by alow)
What's the whole question?

Just think about it, will the same energy heat up a smaller amount of water more or less? Q is the same as you are burning the same amount of fuel, m is just smaller than you think.
From what I understand, less water means less energy is used meaning that as q=mc*delta T. Hence q is lower as a result of lower value of m

Thanks
4. (Original post by coconut64)
From what I understand, less water means less energy is used meaning that as q=mc*delta T. Hence q is lower as a result of lower value of m

Thanks

M won't be decreased because if you don't realise you spilled any, you would assume the mass you measured was correct. So, what will happen to the temperature change if you have a lower mass (but don't realise it)?
5. (Original post by alow)

M won't be decreased because if you don't realise you spilled any, you would assume the mass you measured was correct. So, what will happen to the temperature change if you have a lower mass (but don't realise it)?
Well, in that case it wouldn't change so it would be the same? However, do can you assume that the student hasn't noticed it ? Thanks
6. (Original post by coconut64)
Well, in that case it wouldn't change so it would be the same? However, do can you assume that the student hasn't noticed it ? Thanks
Yes it would. Does it take more or less energy to heat up a lower mass of water?

Because they would just use the volume of water they had measured, not accounting for the spillage. That's what I think the question is implying.
7. (Original post by alow)
Yes it would. Does it take more or less energy to heat up a lower mass of water?

Because they would just use the volume of water they had measured, not accounting for the spillage. That's what I think the question is implying.
Okay then, thanks .

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: August 28, 2016
Today on TSR

### Anxious about my Oxford offer

What should I do?

### Am I doomed because I messed up my mocks?

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
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