If you compare Ice and Water, the better conductor is obviously water. But why water is the better conductor than Ice? water contains very few ions which are responsible for conduction of electricity.
Note: Pure water means water that does not contain ions. This water is water used in batteries. This water is not suitable for drinking. On the other hand, water that contains ions is called impure water. Our drinking water is actually impure water.
Case-1: When water is pure. Also called de-ionized water.
Actually, water contains very few ions which are responsible for conduction of electricity. The conductivity depends on the number of free ions. The number of ions in water is very less. As a result conductivity of water is poor. On the other hand, In ice, the ions are not as free to move about as in a liquid. As a result, the conductivity decreases. The conductivity decreases because the number of ions is reduced at the lower temperature. So, both ice and water are poor conductors of electricity. But on a relative scale, liquid water is a better conductor than ice.
Case-2: When water is not pure.
Water that we use in our daily life activities like drinking water, tap water, etc is not pure water. It contains many salts which ionize in water to form free ions. These free ions can easily move around in the liquid water and hence acts as a good conductor of electricity. On the other hand, when we freeze that water, the ions are no longer move about as freely, so it becomes a poor conductor of electricity.
- Pure water and ice: Poor conductors of electricity.
- Impure water: Good conductor.
- Impure ice: Poor conductor of electricity.