# Enthalpy analysis questionsWatch

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#1
I'm doing a homework sheet on enthalpy of combustion of ethanol and am stuck on some of the analysis questions, I'm not sure if my answers are right

The experiment is heating a set volume of water with a set mass of ethanol and gives a temperature change of 25K. The water is heated for 4 minutes and the maximum temp is recorded

1) If the starting temperature is changed to 80 decrees Celsius what is the effect on the enthalpy change?
- would the enthalpy change become less exothermic because either the temp has a maximum of 100oC or because some of the water evaporates?

2) What would happen to the enthalpy if the water is heated for longer than 4 minutes?
- become more exothermic as the temperature could reach a higher volume? or less exothermic as more ethanol is burnt with no temperature change?

3) what would the effect be if a smaller volume of water was used?
- no change as the equation would be adjusted to compensate for this

Thanks for any help
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4 years ago
#2
I would put the same for questions 1 and 3 but I think that for question 2 the enthalpy change wouldn't really change because as the temperature increases the mass decreases so when you work out Q it shouldn't be too different
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