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The limestone cycle PowerPoint PPT Presentation


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The limestone cycle. Limestone. Learning Objectives. By the end of the lesson I will be able to: Carry out thermal decomposition of calcium carbonate Draw a flow diagram of the limestone cycle Write balanced chemical equations for reactions in the limestone cycle . Heating limestone. - PowerPoint PPT Presentation

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The limestone cycle

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The limestone cycle l.jpg

The limestone cycle

Limestone


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Learning Objectives

By the end of the lesson I will be able to:

  • Carry out thermal decomposition of calcium carbonate

  • Draw a flow diagram of the limestone cycle

  • Write balanced chemical equations for reactions in the limestone cycle


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Heating limestone

  • When limestone (calcium carbonate) is heated, it breaks down (decomposes)

  • When something breaks down with heat we call this reaction…

    Thermal decomposition

  • Calcium carbonate breaks down into calcium oxide (quicklime) and carbon dioxide


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Thermal decomposition of limestone

Calcium heat calcium carbon

Carbonateoxide dioxide

CaCO3heatCaO CO2


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Reacting quicklime with water

  • Calcium oxide (quicklime) is a strong alkali

  • It reacts with water to form calcium hydroxide Ca(OH)2

  • Calcium hydroxide is also known as slaked lime


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Making cement, mortar and concrete.

Decomposing rotting bodies in mass graves and reducing the smell !

Uses for quicklime


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Making Slaked Lime

calcium + water calcium

oxide hydroxide

CaO + H2O Ca(OH)2


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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

Uses for slaked lime


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Limewater

  • Limewater is a solution of calcium hydroxide

  • It is used to test for carbon dioxide

  • 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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Testing for carbon dioxide

calcium + carbon calcium + water

hydroxide dioxide carbonate

Ca(OH)2 + CO2 CaCO3 + H2O


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The Limestone Cycle

These reactions all make up the

limestone cycle.


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Task:

Use the worksheet called ‘The Limestone

Cycle’

- fill in the gaps and complete the

equations for the reactions of limestone.

Stick into your books.


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The Limestone Cycle

limestone

carbon

dioxide

heat

quicklime

limewater

more

water

water

Slaked lime