Question

Design and perform an experiment to show and compare that water always contains hydrogen and oxygen in the same ratio, regardless of its source.

Answer 1

Experiment: Take equal quantities of water from different sources, such as tap water, rainwater and river water. Perform electrolysis of each sample separately using the same apparatus.

Observation: In each case, hydrogen and oxygen gases are collected in the volume ratio of 2:1.

Conclusion: Water always contains hydrogen and oxygen in a fixed ratio of 2:1 by volume (1:8 by mass), regardless of its source.

Instructions and Suggestions:

• Use clean water samples and the same experimental conditions.
• Add a small amount of dilute sulphuric acid to improve electrical conductivity.
• Perform the experiment under teacher supervision.
• Compare the volumes of gases collected from each sample.