Changing States: Melting and Freezing

The Effect of Heat

The state of water can be changed by adding or removing heat (heating or cooling).

1. Melting

• Process: Changing from Solid $\rightarrow$ Liquid.
• Action: Heating (or absorbing heat from surroundings).
• Example: Ice left out of the freezer turns into water.

2. Freezing

• Process: Changing from Liquid $\rightarrow$ Solid.
• Action: Cooling (removing heat).
• Example: Putting water in the freezer to make ice.

3. Evaporation

• Process: Changing from Liquid $\rightarrow$ Gas.
• Action: Heating.

4. Condensation

• Process: Changing from Gas $\rightarrow$ Liquid.
• Action: Cooling.

Cycle of States

The diagram below shows how water changes states based on heating and cooling.

Other Examples in Nature

• Wax: A candle melts (solid to liquid) when lit and solidifies again when cooled.
• Coconut Oil: Often freezes (solidifies) in winter and melts in summer.