"Solids, Liquids & Gases" Return to list of pracs

Aim: This is to illustrate the difference between solids, liquids and gases.

Equipment: The equipment includes...  

• bricks, rulers, chocolate, salt, rocks,
• sauce, cream, cordial, milk, oil, honey,
• a balloon filled with air, a bottle of soda water, an aerosol can, a lit candle and a cup of hot water.
• bike tyre tube and bike pump.

Method: Make 3 posters with "Solids", "Liquids" and "Gases" on the top of the posters by making a cloud shape for gases; a bottle shape for liquid and a block shape for solids. Categorize the following items onto the posters as solids, liquids and gases: bricks, rulers, chocolate, salt, rocks, sauce, cream, cordial, milk, oil, honey, a balloon filled with air, a bottle of soda water, an aerosol can, a lit candle and a cup of hot water. Students could blow up balloons, tyre tubes with bike pumps, observe smoke from candles, using aerosol pumps, pouring liquids or exploring the "runniness" of liquids like water, honey, maple syrup or glass. Get students to try to classify the features that make a solid a solid, a liquid a liquid and a gas a gas. What are your reasons for placing the various objects in the various categories.

Background knowledge: Solids can be tapped; liquids can be poured; and gases float. All matter is one of the three physical states: solid, liquid and gas. Its structure depends on temperature. All substances start as solids at the very lowest possible temperature, absolute zero (-273°C) and go through changes of state as they are heated. As a solid is heated, it will generally melt to become a liquid, and then boil to form a gas. Solids have a definite shape. Liquids take up the same volume within shape of its container even though the shape may change. Gases also do the same except they will always take up the same volume as that of the container. Gases can therefore be squeezed into a smaller container. Solids and liquids cannot.