TESTING FOR GASES Testing hydrogen gas oxygen gas

TESTING FOR GASES Testing hydrogen gas, oxygen gas and carbon dioxide gas

LEARNING GOALS I will be able to distinguish between oxygen, hydrogen and carbon dioxide gases by their chemical properties. You Tube Video Gas Tests: Science Xperiments

PHYSICAL PROPERTIES OF GASES Gases are difficult to tell apart by their physical properties because they are usually: Odourless AND Colourless Therefore to tell gases apart we must use their chemical properties.

OXYGEN GAS Oxygen gas can be produced by combining hydrogen peroxide and manganese dioxide. The manganese dioxide causes the hydrogen peroxide to bubble rapidly creating oxygen gas and water. This happens naturally, but the manganese dioxide increases the speed of the break down. A positive test for oxygen gas is that oxygen will re-light a glowing splint.

HYDROGEN GAS Hydrogen gas can be formed by combining magnesium and hydrochloric acid to produce magnesium chloride and hydrogen gas. A positive test for hydrogen gas is a “squeaky pop” sound is heard as the hydrogen gas is lit. The splint must be burning.

CARBON DIOXIDE GAS Carbon dioxide gas can be formed by mixing calcium carbonate with hydrochloric acid forming calcium chloride, water and carbon dioxide gas. Limewater is a colourless liquid, but when combined with carbon dioxide limewater goes a cloudy/milky colour. When carbon dioxide is bubbled through the limewater it goes opaque.

Carbon dioxide will also affect a flame. It will put a flame out. For this reason carbon dioxide gas is used in some fire extinguishers.

CHEMICAL PROPERTIES OF GASES In summary: To be able to identify gases their chemical properties must be used. Typically the chemical property that is the most useful is combustibility.