Limestone

Question 1

What is limestone formed from?

Answer 1

Sea shells

Question 2

How is limestone gotten?

Answer 2

It is quarried out of the ground

Question 3

Uses of limestone?

Answer 3

• Building blocks
• Powdered limestone is heated in a kilm with powdered clay to make cement
• Cement can be mixed with sand and water to make mortar. Mortar is used to stick bricks together (you can also add calcium hydroxide to mortar)
• You can mix cement with sand and aggregate (water and gravel) to make concrete

Question 4

What is limestone mainly made of?

Answer 4

Calcium carbonate

Question 5

What happens to limestone when it’s heated?

Answer 5

It thermally decomposes to make calcium oxide and carbon dioxide

Calcium carbonate → Calcium Oxide + Carbon Dioxide

Question 6

What is thermal decomposition?

Answer 6

When one substance chemically changes into at least 2 new substances when it’s heated

Question 7

When carbonates are heated what do they produce?

Answer 7

An oxide of their metal (eg magnesium oxide) and carbon dioxide

→ They decompose in the same way

Question 8

Which carbonates decompose in the same way?

Answer 8

Magnesium, copper, zinc and sodium

Question 9

What does calcium carbonate produce when reacted with acid?

Answer 9

It makes calcium salt, carbon dioxide and water

Calcium Carbonate + Sulfuric Acid → Calcium Sulfae + Carbon Dioxide + Water

Question 10

What does the type of salt produced when a carbonate reacts with an acid depend on?

Answer 10

It depends on the type of acid

→ Eg a reaction with hydrochloric acid would make a chloride

Question 11

What does calcium oxide react with water to produce?

Answer 11

Calcium hydroxide

Question 12

Good things about limestone?

Answer 12

• It provides things people want - like houses and roads, chemicals used in making dyes, paints and medicines also come from medicine
• Limestone products are used to neutralise acidic soil. Acidity in lakes and rivers caused by acid rain is also neutralised by limestone products
• Limestone is also used in power station chimneys to neutralise sulfur dioxide, which is a cause of acid rain
• The quarry and associated buisinesses provide jobs for people and bring more money into the local economy. This can lead to local improvements in transport, roads, recreation facilities and health
• Once quarrying is complete, landscaping and restoration of the area is normally required as part of the planning permission

Question 13

What can be used to neutralise acidic soil in fields?

Answer 13

Calcium hydroxide: It is an alkali, and is therefore used to neutralise acidic soil in fields

Powdered limestone

→ Calcium hydroxide works much faster than powdered limestone

Question 14

What can calcium hydroxide be used for?

Answer 14

In a test for carbon dioxide

→ If you make a soultion of calcium hydroxide in water (called limewater) and bubble gas through it, the solution will turn cloudy if there’s carbon dioxide in the gas

The cloudyness is caused by the formation of caclium carbonate

Also to neutralise acidic soil

Question 15

Problems with quarrying limestone?

Answer 15

• It makes an hole which is eye sore, which permanently changes the landscape
• Quarrying processes, like using explosives makes pollution by making dust and noise in quiet, senic areas
• Quarrying destroys habitats of animals and birds
• Noise and pollution comes from transporting the limestone
• Waste materials produce unsightly tips

Question 16

Problems with making stuff from limestone?

Answer 16

• Cement factories make a lot of dust, which causes breathing problems for some people
• Energy is needed to produce cement and quicklime

→ The energy is likely to come from burning fossil fuels; which causes pollution

Question 17

Advantages and disadvantages of limestone products?

Answer 17

• Limestone is widely avaliable and cheaper than granite or marble - it is a fairly easy rock to cut
• Some limestone is more hardwearing than marble, but it still looks attractive
• Concrete can be poured into moulds to make blocks or panels that can be joined together. It is a very quick and cheap way of constructing buildings BUT it is a very unattractive building material
• Lime stone, concrete and cement don’t rot when they get wet like wood does

→ They can’t be gnawed by insects or rodents either, and they’re fire resistant

• Concrete doesn’t corrode like lots of metals do. It does have a fairly low tensile strenght and can crack. If its reinforced with steel brds it’ll be much stronger