C1 - Limestone Flashcards
What is the main use of limestone?
It is usually used for making building blocks and bricks
What is limestone made of?
Mainly calcium carbonate (CaCO^3)
What happens when calcium carbonate is heated?
It thermally decomposes into calcium oxide and carbon dioxide
What happems when calcium carbonate reacts with an acid?
A calcium salt, carbon dioxide and water are formed
What decides the type of calcium salt produced?
The type of acid
E.g. Sulfuric acid makes calcium sulfate
Which carbonates also thermally decompose and react with acid in the sane ways as calcium carbonate?
Magnesium, copper, zinc and sodium carbonates
What happens when calcium oxide reacts with water?
Calcium hydroxide is formed
What is the pH of calcium hydroxide?
It has an alkaline pH because it is a hydroxide
What are the 2 uses of calcium hydroxide?
Neutralise acidic soil in fields
Test for carbon dioxide
Why is calcium hydroxide used instead of powdered limestone to neutralise acidic soil?
It neutralises the acidity much faster
What is limewater?
Calcium hydroxide solution
How is calcium hydroxide used to test for carbon dioxide?
If gas is bubbled through limewater, the solution will turn cloudy if carbon dioxide is present
The cloudiness is because calcium carbonate is being formed
What is the chemical reaction for calcium hydroxide reacting with carbon dioxide?
Calcium hydroxide + carbon dioxide –> calcium carbonate + water
What is the limestone cycle?
The way that calcium carbonate becomes calcium oxide which becomes calcium hydroxide which becomes calcium carbonate again
What are the 3 other uses of limestone?
Powdered limestone and powered clay are heated in a kiln to form cement
Cement is mixed with sand and water to make mortar to hold bricks together
Cement is mixed with sand and aggregate (gravel and water) to make concrete
What are the 5 disadvantage of quarrying limestone?
Makes ugly holes in the landscape
The process makes lots of dust and noise
Destroys habitats
Transported by lorries causing more noise and pollution
Waste materials produce ugly tips
What are the 2 reasons that making things out of limestone causes pollution?
Cement factories make a lot of dust causing breathing problems
Energy is needed to make cement which comes from burning fossil fuels
What are the 5 advantages of limestone?
Provides roads, houses and some chemicals
Used to neutralise acidic soil and acidity in lakes and rivers
Used in industrial chimneys to neutralise sulfur dioxide to prevent acid rain
The quarry industry provides jobs for people
Once quarrying is complete, landscaping and restoration of the area is legally required
Give 6 advantages of limestone products
Perfect for building materials
Widely available and cheaper than marble and granite
More hard-wearing than marble but still attractive
Concrete can be poured into moulds to make blocks which is quick and easy
Limestone, concrete and cement don’t rot like wood when it gets wet
Concrete doesn’t corrode
How do we make concrete stronger?
Reinforce it with steel bars
What is the problem with building houses out of limestone?
Limestone reacts with sulfuric acid to form calcium sulfate, carbon dioxide and water meaning that acid rain destroys limestone
How do we get limestone?
It is quarried out of the ground
