Question

Is water a compound or mixture? Give two reasons in support of your answer.

Answer 1

Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ is a compound because:

• Water is made up of two elements combined chemically i.e.; Hydrogen $\left(\mathrm{H}\right)$ and Oxygen $\left(\mathrm{O}\right)$ having a fixed composition of 2:1 where 2 atoms of hydrogen have combined with 1 atom of oxygen or 1:8 by mass.
• The properties of the water are different from its elements i.e.; hydrogen and oxygen. Example: Water is a liquid whereas hydrogen and oxygen are gases.
• Water can not be broken down into its elements by physical processes. So a process like electrolysis (breakdown of a substance using electricity) is required.

In a mixture, none of the above properties are shown as:

• A mixture has no fixed composition.
• A mixture retains the properties of the constituent elements or compounds.
• A mixture can be separated using physical methods of separation.