Calculating Oxygen in the Air - Non-Metal
Chemistry: Edexcel IGCSE, topic 9.1.3
Calculating the Percentage of Oxygen in the Air
You need to be able to calculate the percentage of oxygen in the air from the reaction of a non-metal, like phosphorus, with air.
Preparation
- Float a piece of white phosphorus on a watch glass in a trough of water.
- Place a bell jar over the watch glass and mark the water level outside.
- Using a glass rod, tip the watch glass so that the phosphorus touches the water.
- Quickly place a bung in the top of the bell jar.
Recordings
- When the reaction has finished, mark the level that the water has risen to.
- Determine the volume of gas before and after by filling the bell jar with water and measuring the volume for each mark made.
- Subtract the final volume from the initial volume to determine the volume of oxygen.
- Divide this value by the initial volume and multiply by 100 to calculate the percentage of oxygen in the air.
Test yourself on Calculating Oxygen in the Air - Non-Metal
The Percentage of Oxygen in the air