Limestone and Building materials

Question 1

What is limestone and how do we get hold of it?

Answer 1

A fairly soft rock, mainly calcium carbonate (CaCO3)

Quarrying

Question 2

Describe the process of thermal decomposition of calcium carbonate.

How is this done on a large scale?

Answer 2

When CaCO3 is heated strongly, it decomposes forming calcium oxide and carbon dioxide.

This is done on a large scale in lime kilns.

Question 3

Which four metal carbonates decompose in a similar way to calcium carbonate?

Which two group 1 metals do not decompose in the heat of a bunsen burner flame?

Answer 3

Magnesium, copper, zinc, sodium

Sodium carbonate and potassium carbonate

Question 4

What is calcium hydroxide, what type of substance is it and what is its formula?
How can it be used, and how is it formed in the limestone cycle?

Answer 4

Slaked lime, an alkali, Ca(OH)2
Neutralisation of acids e.g. used by farmers to neutralise acidic soils and used in industry to neutralise acidic gases.
Calcium hydroxide (slaked lime) is formed when water is added to calcium oxide.

Question 5

What happens when more water is added to slaked lime?

What is the final stage of the limestone cycle?

Answer 5

Calcium hydroxide is not very soluble in water but dissolves slightly to make limewater.
Calcium hydroxide solution in water (limewater) reacts with carbon dioxide to reform calcium carbonate.

Question 6

What happens when carbonates react with acids?

Give one disadvantage of using limestone as a building material?

Answer 6

The reaction produces carbon dioxide, a salt, and water

Limestone is damaged by acid rain, because the carbonate in the limestone reacts with the acids in the rain.

Question 7

How is cement made?

Answer 7

Limestone is mixed with clay and heated strongly in a kiln.

Question 8

How is mortar made? What is it used for?

Answer 8

Cement is mixed with sand and water to make mortar, it is used to hold bricks and blocks together in buildings.

Question 9

How is concrete made? How can it be used?

Answer 9

Cement is mixed with sand, aggregate and water; small stones or crushed rock are used as aggregate.
The mixture can be poured into moulds before it sets to form a hard solid.

Question 10

Give two positive and four negative environmental effects of using limestone.

Answer 10

Positive: 
1) Limestone buildings look attractive.
2) Disused quarries can be regenerated in a number of ways, e.g. resevoir or activities centre.
Negative: 
1) Quarrying destroys habitats
2) Blasting noise can scare off wildlife
3) Creates noise and air pollution

Question 11

Give two positive and two negative social effect of using limestone.

Answer 11

Positive:
1) Quarrying creates jobs
2) Limestone has many uses, it is a useful building material
Negative:
1) Quarrying causes noise pollution which can disturb local residents
2) Quarries often scar the landscape.

Question 12

Give three positive and one negative economic effect of using limestone.

Answer 12

Positive:
1) Limestone and its products have many uses and can be sold
2) Disused quarries can be turned into tourist attractions/adventure parks
3) Quarrying creates jobs - residents have more money to spend
Negative:
1) Disused quarries may spoil the landscape and adversely affect tourism.

Question 13

What is the test for carbon dioxide?

Answer 13

Limewater turns cloudy in the presence of carbon dioxide because it reacts with carbon dioxide to produce insoluble calcium carbonate.