What is thermal decomposition
compound splits into two or more by heat
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Sodium carbonate
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Colour before heating
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Colour after heating
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Gas evolved
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Ease of decomposition
Very difficult
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Calcium carbonate
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Colour before heating
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Colour after heating
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Gas evolved
carbon dioxide
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Ease of composition
fairly easy
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Copper carbonate
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Colour before heating
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Colour after heating
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Gas evolved
Carbon dioxide
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Ease of decomposition
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Copper is the... reactive metal and decomposes...
least. Rapidly
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The more reactive the metal...
the more stable the carbonate
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Calcium is... reactive than sodium therefore heat is able to decompose calcium carbonate...
less. fairly easy
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... observed with... as the more reactive the metal makes the carbonate more stable
no reaction. Sodium carbonate
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Limestone cycle
stage 1, 2 and 3
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Stage 1
Roast the limestone for 20 mins. Limestone glows and becomes crumbly. This decomposes it to calcium oxide, quicklime.
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Stage 2
Add a few drops of water to the calcium oxide (quicklime). This causes the compound to sizzle and release steam. This forms calcium hydroxide, slaked lime. The reaction is exothermic
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Stage 3
Add excess water. Calcium hydroxide (slaked lime) dissolves a little in water. Excess water is added to form and alkaline solution called limewater
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The reaction of limewater with carbon dioxide
Limewater turns milky if carbon dioxide gas is present. Carbon dioxide passes into lime water gives a milky solution
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Give 5 examples of what limestone is used for in raw materials
-Used to make cement when mixed with clay or sandstone. -Quicklime and slaked lime are added to acidic lakes to improve diversity of aquatic life.-Used to make glass.-Used in toothpaste as an abrasive.-Used to neutralise and raise pH of acidic soils.
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What are the effects of quarrying (disadvantages)
Formation of dust. Noise due to rock blasting. Increased trafficking with heavy lorries. Landscape becomes unsightly. Destroys wildlife
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Sodium carbonate



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Colour before heating


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Colour after heating


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Card 5


Gas evolved


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