l.o: to know what limestone is and how it can be decomposed using heat
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L.O: To know what limestone is and how it can be decomposed using heat
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Limestone Marble Calcium carbonate Chalk Calcite Travertine Tufa Limeshell Coral Marl
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Limestone is a sedimentary rock.
It comes from the shells of sea creatures or from solids formed in the oceans long ago.
It is mostly made of calcium carbonate - CaCO3.
It is an important raw material for both the chemical and the construction industries.
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What do you predict? Look at the available equipment for a hint!
What do you think the word equation is?
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1. Making quicklime from limestone
Heat a spatula of calcium carbonate in a test tube. Clamp the test tube above the bunsen and use a delivery tube connected to limewater to see if carbon dioxide is given off.
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Quicklime - the lime kilnQuicklime - the lime kiln
• Limestone is heated in huge ovens known as lime kilns.
• The calcium carbonate decomposes into calcium oxide (quicklime) and carbon dioxide.
• Quicklime is a vital ingredient of cement, concrete and of most types of glass.
CaCO3 CaO + CO2
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Water can now be added. What would the word equation be now?
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Slaked limeSlaked lime
• If water is added to quicklime the calcium oxide changes into calcium hydroxide (slaked lime).
• Slaked lime is a vital ingredient of various building materials.
CaO + H2O Ca(OH)2
• A solution of calcium hydroxide (limewater) is also used to test for carbon dioxide gas (it goes cloudy).
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Limestone Cycle experimentLimestone Cycle experiment
2. Turning quicklime into slaked limeTip the quicklime into a watch glass and add a few drops of
water. Test this substance with UI. If calcium hydroxide has been made (an alkali) the UI will go purple.
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The “Limestone Cycle”The “Limestone Cycle”Calcium Carbonate
(limestone)
Calcium Oxide
(lime or quicklime)
Calcium Hydroxide
(slaked lime)
Calcium Hydroxide solution
(limewater)
Step 1: heat
Step 2: add a little water
Step 3: add more water and
filter
Step 4: add CO2
CO2
CO2
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LimestoneLimestoneIf soil is too _____ crops will fail. Limestone can also be used as a neutralising agent. There are two reactions to know:
1) Firstly, a THERMAL _________________ reaction is used to break the calcium carbonate down into calcium oxide (quicklime) and _______ __________:
2) This is then “slaked” with water to produce calcium hydroxide (“_________ lime”):
Calcium hydroxide is alkaline and is used to ______ acidic soil.
Calcium carbonate calcium oxide + carbon dioxideHEAT
Calcium oxide + water calcium hydroxide
Words – slaked, acidic, neutralise, decomposition, carbon dioxide