What is always conserved when a substance undergoes a change of state
Sublimation
When a solid changes into a gas without passing through a liquid state
Condensation
When a gas changes into a liquid state
Water boils in an open pan
Some of the water will evaporate and turn into water vapour, leaving the pan and decreasing the mass of the pan. The mass of the whole system however remains constant.
Bathroom mirror mists up
1. Hot water evaporates to form water vapour
2. This water vapour lands on the cooler mirror
3. The vapour condenses and returns to liquid state on the mirror's surface
