Question

What happens to water if

(a) it is kept in a deep freezer?

(b) it is heated?

Explain the phenomenon of change of state of water.

Answer 1

(a) When water is kept in a deep freezer, it gets cooled and changes into ice at 0°C.

$Water\underset{0^{o}C}{\overset{Deepfreeze}{\to }}Ice$

(b) Water on heating changes into steam at 100°C.

$Water\underset{{100}^{o}C}{\overset{Heating}{\to }}Steam$

The phenomenon of change of state of water:
Water is a liquid under ordinary conditions but, when water is kept in a deep freezer, it changes into ice at 0°C and when ice is kept at room temperature again changes back into liquid water.
Similarly, water on heating changes into steam at 100°C, which on cooling changes back into liquid water. But there is no change in the chemical composition of water. So, these are an example of physical change because only the physical state of the compound change while the chemical composition remains the same.