C1 - Limestone

Question 1

What is the main use of limestone?

Answer 1

It is usually used for making building blocks and bricks

Question 2

What is limestone made of?

Answer 2

Mainly calcium carbonate (CaCO^3)

Question 3

What happens when calcium carbonate is heated?

Answer 3

It thermally decomposes into calcium oxide and carbon dioxide

Question 4

What happems when calcium carbonate reacts with an acid?

Answer 4

A calcium salt, carbon dioxide and water are formed

Question 5

What decides the type of calcium salt produced?

Answer 5

The type of acid

E.g. Sulfuric acid makes calcium sulfate

Question 6

Which carbonates also thermally decompose and react with acid in the sane ways as calcium carbonate?

Answer 6

Magnesium, copper, zinc and sodium carbonates

Question 7

What happens when calcium oxide reacts with water?

Answer 7

Calcium hydroxide is formed

Question 8

What is the pH of calcium hydroxide?

Answer 8

It has an alkaline pH because it is a hydroxide

Question 9

What are the 2 uses of calcium hydroxide?

Answer 9

Neutralise acidic soil in fields

Test for carbon dioxide

Question 10

Why is calcium hydroxide used instead of powdered limestone to neutralise acidic soil?

Answer 10

It neutralises the acidity much faster

Question 11

What is limewater?

Answer 11

Calcium hydroxide solution

Question 12

How is calcium hydroxide used to test for carbon dioxide?

Answer 12

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

Question 13

What is the chemical reaction for calcium hydroxide reacting with carbon dioxide?

Answer 13

Calcium hydroxide + carbon dioxide –> calcium carbonate + water

Question 14

What is the limestone cycle?

Answer 14

The way that calcium carbonate becomes calcium oxide which becomes calcium hydroxide which becomes calcium carbonate again

Question 15

What are the 3 other uses of limestone?

Answer 15

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

Question 16

What are the 5 disadvantage of quarrying limestone?

Answer 16

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

Question 17

What are the 2 reasons that making things out of limestone causes pollution?

Answer 17

Cement factories make a lot of dust causing breathing problems

Energy is needed to make cement which comes from burning fossil fuels

Question 18

What are the 5 advantages of limestone?

Answer 18

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

Question 19

Give 6 advantages of limestone products

Answer 19

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

Question 20

How do we make concrete stronger?

Answer 20

Reinforce it with steel bars

Question 21

What is the problem with building houses out of limestone?

Answer 21

Limestone reacts with sulfuric acid to form calcium sulfate, carbon dioxide and water meaning that acid rain destroys limestone

Question 22

How do we get limestone?

Answer 22

It is quarried out of the ground