Chemical Tests for Water

Water is not the only clear colourless liquid; it can be difficult to tell if a liquid has water in it.

This demonstration shows the two main chemical tests for water.

1. Water turns anhydrous copper sulfate (white) into hydrated copper sulfate (blue).

2. Water turns anhydrous cobalt chloride (deep blue) into hydrated cobalt chloride (pale pink).

There is also a physical test for pure water, not shown in this video. This test involves measuring both the melting and boiling points. Water is the only substance that melts and boils at exactly 0 °C and 100 °C respectively.