[inexplicable]

Hypothesis: The alcohol with the longer carbon chain, ethanol releases more heat energy than methanol.

Aim: By varying the type of alcohol used to heat up water, the change in temperature is recorded and used to calculate heat enthalpy of each individual alcohol and then comparing them.
My experiment's procedures are similar to this: http://www.practicalchemistry.org/experiments/measuring-heat-energy-of-fuels,21,EX.html

However, I'm having abit of trouble figuring out how much (no. of mols) alcohol i should use. I'm keeping the no. of mols for each alcohol constant and burning them separately but each time, the aim is to raise the temperature of water. But I don't want the water to reach boiling point, I was wondering how many mols I should use to avoid this?
I'm using methanol,ethanol,propanol,butanol and pentanol.

Thanks for your time!

[kittydalt]

I also have the same question!

[bakerbg]

Finding the MOLAR heat enthalpy is the final step. What you need to find first is the energy change for a particular mass of alcohol- any mass.

 Energy change = mass x specific heat capacity of H2O x temperature change

 Work out the molar mass and then deduce the energy change that would occur if that amount was used. Compare the molar enthalpy change for each alcohol.


Alternatively, as the website suggests, just determine the mass of alcohol which produce a reasonable temperature change, say about 40^oC? The alcohol that requires the less mass produces more heat energy.