A decomposition reaction is one in which a compound breaks down into simpler compounds or elements.
Thermal means by heating it.
No atoms are lost or made when a thermal decompostion reaction takes place. The mass of the products, if they can be trapped, is the same as the mass of the reactants.
1. Limestone is a natural rock made mainly of calcium carbonate
Calcium Carbonate -heat strongly-> Calcium Oxide + Carbon Dioxide
CaCO3(s) --> CaO + CO2
2. Calcium Oxide + Water -slaking(add water)-> Calcium Hydroxide
CaO(s) + H2O(l) --> Ca(OH)2(s)
3. Calcium Hydroxide + more water -shake with water and filter, use solution-> Calcium Hydroxide solution
Ca(OH)2 + aq(solvent water) --> Ca(OH)2(aq)
4. Calcium Hydroxide solution + Carbon Dioxide(bubble through CO2) --> Calcium Carbonate + Water
Ca(OH)2 + CO2 --> CaCO3(s) + H2O limestone looks cloudy
Uses of Limestone
As a building material:
- Houses and road foundation (direct use)
- Limestone grinded up with clay and mix to powder -heat, rotating kiln-> cement
- Cement is laid to make paths or fill cracks in buildings
- Cement + sand -mix-> mortar (to hold together bricks).
- Cement + sand + agregat(gravel) -mix-> concrete. Concrete is used to make buildings. It is cheaper than limestone.
- Limestone can be turned into calcium hydroxide by adding heat and water. Calcium Hydroxide neutralises acid farm soil, neutralises excess acidity
Advantages and Disadvantages of a quarry
- Used for buildings
- Creates jobs
- Improve local roads
- Leaves visual scars on landscape
- Explosives used make noise and dust
- Scare off wildlife
- Noise pollution
- Looks ugly
- Destroys animal wildlife