Changing States of Water
Melting
When ice is taken out of the freezer, the ice will melt. When ice melts, it gains heat.
The temperature at which ice turns into water is called the melting point of water.
There is a change of state from solid to liquid.
Freezing
Water changes to ice by freezing. When water is put into the freezer, it loses heat.
The temperature at which water turns into ice is called the freezing point of water.
There is a change of state from liquid to solid.
Boiling
When water is boiled, it changes into steam.
The temperature at which water turns into steam is called the boiling point of water.
There is a change of state from liquid to gas.
Condensation
The process in which a gas changes into a liquid is called condensation.
Steam and water vapour in the air condenses into tiny drops of moisture on cool surfaces. When water vapour is cooled, it forms tiny drops of water.
Clouds are formed from the condensation of water vapour high up in the sky.
Condensation also occurs on a glass containing ice when water vapour comes into contact with the cold glass.
Evaporation
Evaporation is a process when liquid changes to gas. Evaporation takes place all the time.
For example, a dish of water when left in the room will be evaporated into the air as water vapour.
Rate of Evaporation
The rate of evaporation depends on the following factors:
Wind condition: Wind increases the rate of evaporation.
Temperature of the surrounding: When the surroundings are hot, evaporation will take place faster.
The area of the exposed surface: the bigger the exposed surface area of the liquid, the faster the liquid will evaporate.
Humidity: The amount of water vapour in the air is called its humidity. Evaporation happens more slowly if humidity is high.
