Heat of Combustion

The heat of combustion: It is the energy change of a reaction when a substance is burnt.

Experiment:

STEP 1) Use a calorimeter and a spirit burner.

STEP 2) Heat a known volume of water with a flame from the burning ethanol.

STEP 3) Measure the temperature rise of the water.

This type of experiment is useful to compare the different fuels to see which would give the most heat to warm known amount of water 

Controls:

Amount of liquid put in the spirit burner should be controlled.

POLYSTYRENE is a good insulator and is therefore used as a calorimeter --> to measure the temperature rise of exothermic reactions between solutions 

EXPERIMENT:

STEP1 )Solutions are mixed in polystyrene cups and initial temperature is measured.

STEP 2) Mixture should be stirred well with a thermometer and measured frequently during the reaction.

STEP 3) Maximum temperature is recorded.

The method can also be adapted for reactions involving:

1) A solid base and an acid 

2) A solid carbonate and an acid

3) Displacement reactions between a metal and a solution of salt of a less reactive metal