6. How would you confirm that a colourless liquid given to you is pure water?
Answer: Solute and solvent have characteristic physical and chemical properties. We can use any suitable property and compare it with the given solution. If the liquid show only the properties of pure water, it confirms the given liquid is pure. Below are the properties of pure water, which we can use to estimate its purity.
- Pure water on boiling leaves no residue.
- pure water freezes exactly at 0°C. Any impurity in water cause more effort in freezing.
- it does not have a smell.
- It does not conduct electricity (Very less/ negligible).
- Pure water does not cause scattering of light (Tyndall effect)
Water reacts with acids, bases and salts and liberates hydrogen gas. (This experiment detects the presence of water but not the purity.)