To confirm that a colourless liquid is pure water, you can perform these main tests:
- Measure the boiling point of the liquid. Pure water boils at exactly 100 degrees Celsius (373 K) at standard atmospheric pressure (1 atmosphere). If it boils at this temperature, it indicates purity.
- Measure the freezing point. Pure water freezes at 0 degrees Celsius (273 K) under the same standard conditions.
- Observe if there is any residue after evaporating the liquid. Pure water leaves no residue after evaporation, indicating no dissolved impurities.
- Check for suspended impurities by filtering the liquid through fine filter paper. No residue means no suspended impurities.
- Optionally, test the electrical conductivity. Pure water has very low conductivity compared to impure water.
Together, these tests confirm the liquid's identity and purity as water.
