Limestone

Decomposition means something breaks down into what it was made from

Thermal means heat

Thermal decomposition mean breaking something down using heat

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

Metal carbonate - metal oxide + carbon dioxide

Zinc carbonate - zinc oxide + carbon dioxide
ZnCO3 ZnO CO2

Copper carbonate - copper oxide + carbon dioxide
CuCO2 CuO CO2

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
Cement
{ 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

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

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

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

Equation:

Carbonate + acid - salt + carbon dioxide + water

E.g
Zinc carbonate + hydrochloric acid - zinc chloride + carbon dioxide + water

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