Aim: To estimate the molar heat of combustion of ethanol
Apparatus:
Method:
1. Record the weight of a spirit lamp, M1.
2. Set up the apparatus in a way that the tin can is supported by a stand and clamp.
3. Pour 100cm3 of water in to the tin can using a measuring cylinder.
4. Record the initial temperature of the water by using a thermometer, 𝜃1
5. Light the spirit lamp.
6. Stir the water in the can gently, using the thermometer.
7. As the temperature rises by 20OC, put out the flame. Record the maximum temperature
which is reached, 𝜃2.
8. Re-weigh the spirit lamp, M2.
Precautions:
Results:
Mass of spirit lamp + ethanol before
burning(M1)
Mass of spirit lamp + ethanol after burning(M2)
Initial temperature of water, 𝜃1
Final temperature of water, 𝜃2
Mass of water, m
Calculations:

Use the formula H= mc∆θ to find the heat supplied to the water.

Then work out the molar heat of combustion by finding the heat produced by 1 mole of
ethanol. ( Remember the RAM’s of C = 12 H= 1 O= 16)
Discussion:

What is the value of molar heat of combustion of ethanol?

Compare the experimental molar heat of combustion of ethanol with the actual molar heat
of combustion of ethanol. Are there any discrepancies between the two values?

Discrepancies between the two values can be due to heat losses. Explain where there could
be heat losses in the set up.