Specified practical

Investigation of the variation of the volume of a gas with temperature

The volume of a gas varies according to the conditions. If the gas is heated, the gas particles move faster, which increases the volume of the gas. The relationship between volume and temperature will be investigated.

Aim of the experiment

To measure the volume of a fixed mass (amount) of gas at different temperatures.

Method

  1. Set the syringe volume to eg 25 cm3.
  2. Make sure the syringe and flexible tube do not contain any water.
  3. Insert the flexible tubing into the inverted measuring cylinder to collect any gas bubbles given out.
  4. Submerge the syringe in the room temperature water for eg 4 minutes.
  5. Move the syringe into a bowl of water at eg 30°C.
  6. Record the initial volume on the measuring cylinder.
  7. Collect the bubbles of air until they stop.
  8. Record the final reading on the measuring cylinder.
  9. Calculate the difference in the readings. This is the volume of gas produced.
  10. Repeat steps 1 to 9 twice more.
  11. Repeat at further water temperatures, eg 30°C, 40°C and 50°C.
Two bowls, one at room temperature and one at 30 degrees. Both have a thermometer and a syringe in them, with tubing that leads to another bowl with a measuring cylinder to collect gas.

Results

The results can be displayed in a table like the one below:

Temperature of ‘room temperature’ water in bowl in stage 1 (°C)Reading on measuring cylinder at the start (cm³)Temperature of water in bowl in stage 2 (°C)Reading on measuring cylinder at the end (cm³)Volume of gas collected (cm³)
2030

Analysis

Compare how the volume changes at each temperature. Explain the answer in terms of the movement of the molecules.

Evaluation

Measurements of volume of gas collected are subject to experimental error, which could be because:

  • some gas may escape before it can be collected in the upturned measuring cylinder
  • the resolution of the measuring cylinders may be different, causing different values for the volume to be recorded

Risk assessment

HazardRiskControl measures
Hot water can scald.Splashing or spilling hot water on skin can cause a scald.Use heater baths if available for investigating.
Broken glass is sharp.Overtightening the clamp on the glass measuring cylinder may break the cylinder giving a danger of cuts.Take care not to overtighten the clamp. Use plastic as an alternative to glass.