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  • Created by: XxzoexX
  • Created on: 27-04-14 22:02

Key words

Decomposition means something breaks down into what it was made from

Thermal means heat

Thermal decomposition mean breaking something down using heat

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Breaking down carbonates

Ways to tell if a carbohydrate breaks down (decomposes) when heated:
-it gives off carbon dioxide gas (turns limewater milky)
-it changes colour

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Metal carbonate - metal oxide + carbon dioxide

Zinc carbonate - zinc oxide + carbon dioxide

Copper carbonate - copper oxide + carbon dioxide

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Products from limestone

Limestone is calcium carbonate (CaCO3)

1) Limestone itself is used as a building material like bricks
2) heat limestone
CaCO3 - CaO + CO2
This is an example of thermal decomposition reaction
CaO - is useful
{ add clay
{ add sand } sand and gravel
Mortar Concrete
(Used for (Used for foundations)
Brick laying)
3) add water
Calcium hydroxide is made
This is an exothermal reaction. Heat is given off - it fizzes
4)add more water
It makes calcium hydroxide solution this is lime water - it turns milky with carbon dioxide as tiny particles of limestone are made

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The limestone cycle

Calcium carbonate (limestone)

{ step1 heat

Calcium oxide (lime or quick water)

{ step 2 add a little water

Calcium hydroxide (slake water)

{ step 3 add more water and filter

Calcium hydroxide solution (limewater)

{ step 4 add carbon dioxide

Calcium carbonate

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Reasons for quarrying:

  • limestone is need for building trade
  • provide jobs and money for local people
  • limestone is needed to make cement, glass etc...

Reasons against quarrying:

  • will ruin the beauty of the countryside
  • local wildlife would lose their habitat

Ways to limit the problem:

  • trees would be planted around the quarry
  • quarrying would stop at night
  • it would be turned into a fishing lake when finished
  • lorries could be sprayed to keep the dust down
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Limestone and acid

Substance Observation
Sodium carbonate It fizzes, gives off a gas and when you touch the acid it bubbles
Copper carbonate Turns the liquid green, and gives of a gas
Zinc carbonate fizzes, it goes cloudy and the powder sinks to the bottom

The gas made is CO2


Carbonate + acid - salt + carbon dioxide + water

Zinc carbonate + hydrochloric acid - zinc chloride + carbon dioxide + water

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Limestone materials

Material Advantage Disadvantage
Limestone -Easily cut into shape -worn away easily
Concrete -looks attractive -looks unattractive
-does not corrode
Glass -transparent -can be expensive
-breaks down easily

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