Reactions of Calcium Compounds*

ObjectivesDescribe the effect of water on calcium oxideDescribe how calcium hydroxide dissolves in water to form a solution, known as limewater.Explain how calcium carbonate can be used to remove acidic gases from coal-fired power station chimneys, reducing harmful emissions and helping to reduce acid rain.

Hoover DamHow it was made, and which rock would have been quarried to provide concrete for it ?

Place one marble chip on awire gauze.Heat the marble chip very strongly for 10 minutes and then leave it to cool.What changes in the appearance of the marble chip do you notice on heating?

Add 10 cm3 of distilled water and gently shake the mixture. Filter the solution in the boiling tube and keep the filtrate.Take a sample of the filtrate and blow air from your lungs through it using a straw

How does the temperature change when water is added to quicklime?What did you observe when you blew air from your lungs through the solution of slaked lime in water?What gas from your lungs do you think reacted with the slaked lime solution?

When calcium oxide reacts with water, a lot of heat is produced. The solution formed is calcium hydroxide. This solution is often called limewater.

When carbon dioxide is bubbled through it limewater turns cloudy. This is because a precipitate of insoluble white calcium carbonate is formed. A reaction where an insoluble product is made from soluble reactants is called a precipitation reaction. If these reactions happen in a sealed container, the total mass before and after the reaction stays the same.

Calcium hydroxide, calcium carbonate and calcium oxide react with acids and neutralise them. They can be used to reduce the acidity of soil. In coal-fired power station chimneys, calcium carbonate is also used to remove acidic gases like sulfur dioxide. This helps reduce the amount of acid rain.

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