Investigating combustion (Core practical)

Question 1

aim of the practical

Answer 1

to investigate the temperature rise in a known mass of water by the combustion of methanol, ethanol, propanol and butanol

Question 2

special equipment needed

Answer 2

• calorimeter

- spirit lamps containing alcohols

Question 3

calorimeter

Answer 3

a metal can (often made of copper) used to contain water

Question 4

spirit lamp

Answer 4

a small glass container with a wick that is used to burn the liquid inside it

Question 5

setup of the apparatus

Answer 5

• the calorimeter is held above the spirit lamp by a clamp/stand
• the calorimeter contains water and the spirit lamp contains an alcohol
• the calorimeter also contains a thermometer and a stirrer

Question 6

method of the practical

Answer 6

1) add a known volume of water to the calorimeter
2) measure its temperature
3) measure and record the mass of a spirit lamp with, including the fuel and lid
4) place the spirit lamp underneath the calorimeter, at a height where you are able to remove and replace the lid
5) remove the lid of the lamp and light the lid
6) stir the water as it is heated, when the temperature has increased enough (e.g. by a given amount), replace the lid to put out the flame
7) record the water temperature, and the mass of the spirit lamp with the remaining fuel and lid
8) empty the calorimeter and repeat steps 1-7

Question 7

What does the results table look like?

Answer 7

the first column lists the alcohols

the next two columns record the start and end temperature

the next two record the start and end mass of the lamp

Question 8

What other values do you need to know?

Answer 8

• the increase in temperature
• the decrease in mass due to alcohol burning
• the change in temp/change in mass (C/g, degrees per gram, of alcohol burned)