Limestone

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Slide 1

and its uses

Limestone

Slide 2

What is limestone?

It is a sedimentary rock

It was formed mainly from sea shells

It is the compound called calcium carbonate

It is a useful raw material

Slide 3

What can limestone be used for?

Building walls

Building houses

Limestone is also used to make cement and concrete

Neutralising excess acid in lakes or soils

Slide 4

More about limestone

Limestone is dug up out of the ground in quarries

In Britain about 150 million tonnes of limestone are quarried each year

Limestone is the compound calcium carbonate

It’s formula is CaCO3

Limestone can be chemically changed into other things

Slide 5

Heating limestone

When limestone (calcium carbonate) is heated, it will break down (decompose)

When something breaks down with heat we call this reaction a ….

Thermal decomposition reaction

Calcium carbonate will have broken down into calcium oxide and carbon dioxide

We call calcium oxide quicklime

Slide 6

A word equation for this reaction

Calcium heat calcium carbon

Carbonate oxide dioxide

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Reacting quicklime with water

Calcium oxide (quicklime) is a strong alkali

It reacts with water to form calcium hydroxide

Calcium hydroxide is also known as slaked lime

Slide 8

A word equation for this reaction

calcium + water calcium

oxide hydroxide

Slide 9

Uses for slaked lime

To neutralise acidic soils, and to break up the soil so that plants can grow well

To neutralise lakes which have been polluted by acid rain

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Another use for calcium hydroxide

Calcium hydroxide is also called limewater

Limewater is used to test for the presence of carbon dioxide gas

We breathe out a lot of carbon dioxide

If we blow through a straw into limewater it will change from clear to milky-white

The substance formed in this reaction is insoluble calcium carbonate

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