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# Errors in enthalpy change reaction

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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 .

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