What are the uses of limestone?
- Glass- limestone is heated with sand and sodium carbonate
- Buildings and rocks
- Steel- limestone removes impurities in a furnace
- Paper- used to whiten and provide bulk
- Neutraliser- of acidic soil and lakes affected by acid rain
- Cement- heat limestone with clay
- Concrete- add gravel, sand and water to cement
- Mortar- add water and sand to cement
- Chemicals- used in dyes, paints and medicine
What is limestone?
Primarily calcium carbonate- CaCO3
What are the positives of quarrying?
- Provides jobs and employment
- Makes the economic sector richer
- Effective way of extracting a lot of limestone
- Fills demand
- There are sustainable ways to use the site afterward e.g. a lake/ reservoir, regrowth of vegetation, recreational waterpark
- Can lead to local improvements in transport, roads etc
What are the negatives of quarrying?
- Damages the environment
- Affects aesthetic landscapes (visual pollution)
- Pollutes the air- with chemicals and the lorry exhaust fumes from the limestone transportation
- Traffic
- Noise pollution
- Doesn’t attract tourists
What are the negatives of making things from the limestone?
- Cement factories make a lot of dust- can cause breathing problems for local people
- Energy is required to make the products like cement and quicklime which is likely to come from burning fossil fuels- also resulting in pollution
What are the advantages and disadvantages of limestone building materials? (e.g. cement and concrete)
Advantages:
- Limestone is widely available and cheaper than granite or marble
- Limestone is easy to cut
- Some limestone is more hard-wearing than marble but it still looks attractive
- Concrete can be poured into moulds to construct buildings and is also very quick and cheap
- Don’t rot when wet like wood does
- Can’t be gnawed away by insects and rodents
- Fire- resistant
- Concrete doesn’t corrode like a lot of other metals
Disadvantages:
- Concrete is very unattractive
- Has a fairly low tensile strength- requires steel bars to reinforce it
What is good about concrete?
- It resists forces which squeeze or crush it
- Good in building construction
- Can be produced at the correct strength for the job
What are the benefits of wood?
- Could be used for simple homes
- Could be used to make something quickly
- Doesn’t have to be carried over a long distance
- Does not use large amounts of material
- Natural
What happens when a carbonate like limestone reacts with an acid?
Forms a salt, water and gas
e.g. Calcium carbonate + (sulfuric) acid –> calcium (sulfate) + carbone dioxide + water
(1) What is the thermal decomposition of limestone?
Calcium carbonate –>(heat) calcium oxide + carbon dioxide
CaCo3 –> CaO + Co2
(2) What is the reaction of calcium oxide (quicklime) and water?
Calcium oxide + water –> calcium hydroxide
CaO + H2O –> Ca(OH)2
What can calcium hydroxide be used for? (slaked lime)
It is an alkali which can be used to neutralise acidic soil in fields- it works much faster than powdered limestone
(3) What is the test for carbon dioxide?
Make a solution of calcium hydroxide in water (limewater) and bubble gas through it- the solution will turn cloudy if carbon dioxide is present because that is the indication of the formation of calcium carbonate (limestone)
Calcium hydroxide + carbon dioxide –> calcium carbonate + water
Ca(OH)2 + CO2 –> CaCO3 + H2O
Reactions of limestone…(4)
Calcium carbonate: (limestone)
- step 1- heat, carbon dioxide given off, makes…
Calcium oxide: (lime or quicklime)
- step 2- add water, makes…
Calcium hydroxide: (slaked lime)
- step 3- add more water and filter, makes…
Calcium hydroxide solution: (limewater)
- step 4- add carbon dioxide (can be a test) making calcium carbonate again
