Freezing and Melting Solids

Sometimes matter changes its state. For example, a liquid can turn into a solid if it becomes cold enough. This is called freezing. The temperature at which a substance becomes a solid is called its freezing point.

Different liquids become solid at different freezing points. Liquid water becomes solid ice at 32° Fahrenheit (0°C).

When water freezes it takes up more space. Have you ever made your own popsicles with juice? Juice is mostly made of water. If you fill a popsicle tray to the top, the juice will spill out. This is because the water in the juice takes up more space when it freezes.

A solid will change into a liquid if it is heated to a high enough temperature. Changing from a solid to a liquid is called melting. The temperature at which this occurs is a solid’s melting point. When a solid reaches its melting point, its molecules unlock and begin to move freely. The substance becomes a liquid.

Chocolate has a relatively low melting point. It is around 97° F (36° C). At this temperature, chocolate becomes a liquid.View Larger Image

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