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LIMESTONEBY
ABHISHEKJAGUESSAR
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What is limestone?
• It is a sedimentaryrock
• It was formed mainly
from sea shells• It is the compound
called calciumcarbonate
• It is a useful rawmaterial
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What can limestone be used for?
• Building walls
• Building houses
• Limestone is alsoused to makecement and
concrete
• Neutralising excessacid in lakes or
soils
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More about limestone
• Limestone is dug up out of the groundin 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
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Heating limestone
• When limestone (calcium carbonate) isheated, 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
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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
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A word equation for this
reaction
calcium + water calcium
oxide hydroxide
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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 presenceof carbon dioxide gas
• We breathe out a lot of carbon dioxide
• If we blow through a straw into limewater itwill change from clear to milky-white
• The substance formed in this reaction isinsoluble calcium carbonate
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A word equation for this
reaction
calcium + carbon calcium + water hydroxide dioxide carbonate
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The Limestone Cycle
These reactions all make up the
limestone cycle.
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limestone
Slaked lime
quicklimelimewater
heat
water more
water
carbondioxide
The limestone cycle
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Tasks:
Use the worksheet called ‘The LimestoneCycle’ to fill in the gaps and complete the
equations for the reactions of limestone.
Copy out The Limestone Cycle.
Answer questions 1-5 on the nextworksheet
using the information given and your own
Knowledge. Afterwards copy out the
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HOMEWORK
Complete the worksheet on
Questions on Limestone
for next lesson.
