How would, you confirm that a colourless liquid given to you is pure water?

To confirm that a colourless liquid is pure water, you can perform a few simple tests:

Boiling Point Test:

• Pure water has a boiling point of 100°C at standard atmospheric pressure (1 atm).
• Heat the liquid and check if it boils at 100°C.
• If it boils at 100°C, it's likely to be pure water, but if it boils at a significantly different temperature, it may contain impurities or other substances.

Freezing Point Test:

• Pure water freezes at 0°C.
• Place the liquid in a freezer and check if it freezes at 0°C.
• If it freezes at a different temperature, the liquid may not be pure water.

Conductivity Test: 

• Pure water is a poor conductor of electricity because it contains very few ions.
• Use a conductivity tester or a simple circuit with a light bulb to check if the liquid conducts electricity.
• If the liquid does not conduct electricity, it's more likely to be pure water, as impurities usually make water conductive.

Taste Test (Optional but Not Recommended):

• Pure water has no taste, so if you are confident that the liquid is safe, you could taste it.
• Note: This is not a reliable method and should only be done if the source of the liquid is known to be safe.

pH Test: 

• Pure water has a neutral pH of 7.
• Use a pH test strip or pH meter to measure the pH of the liquid.
• If the pH is exactly 7, the liquid is likely pure water, but if it’s above or below 7, the liquid may contain impurities.