Changes in Volume of Matter

Heat also affects the volume of matter. Generally, objects get bigger when they get hotter and get smaller when they cool down. Through expansion, solids increase in size or volume when heat is applied to them.

Note, for instance, how an uncooked siopao will expand when it is exposed to heat and will contract when cooled. The same principle applies to an inflated balloon when it is heated. The balloon’s contents will expand and may even burst when the balloon is inflated beyond its capacity to hold more.

Liquids also expand when heated. You may often find water spilling out of a kettle when the water boils. Heat increases the energy of the water molecules and makes them move faster. In turn, the movement of the molecules causes them to occupy wider space. When the heat is released, the water in the kettle settles.