Limestone and Building Materials

What is limestone?

What do I need to know?

MustState that limestone is mainly composed of the compound calcium carbonate, is quarried and can be used as a building material.ShouldDescribe how calcium carbonate can be decomposed by heating to make calcium oxide and carbon dioxide.CouldExplain the steps in the limestone cycle.

What is limestone?

Limestone is mainly composed of the compound calcium carbonate,

We obtain limestone by quarrying

It is a useful building material

Problems with quarrying

• Quarrying is the method that we use to obtain limestone by using explosives to break it into pieces

• It produces dust which may cause breathing difficulties such as asthma

• It is noisy• It may create more traffic to and from the quarry.• Destroys the landscape and may impact wildlife.

Benefits of quarrying

• Creates local jobs boosting the local economy

• Provides building materials a valuable raw material for cement

The limestone cycle• Heat calcium carbonate (limestone) strongly it thermally

decomposes to form calcium oxideCalcium carbonate

• Calcium oxide is another white powder, it reacts exothermically with water to form calcium hydroxideCalcium oxide

• Calcium hydroxide reacts with more water to form calcium hydroxide solution .Calcium hydroxide

• Calcium hydroxide solution is known as limewater and is used as a test for carbon dioxide.

Calcium hydroxide solution

• The cloudy substance formed when carbon dioxide is bubbled through limewater is calcium carbonate or limestone.Calcium carbonate

Step 1 - Heating limestone

Thermal Decomposition

• Copy and complete this equation.

CaCO3 _______ + CO2

• Write down the word equation for the process

• This is the FIRST STEP in the limestone cycle.

Calculations of mass

This question should be a little bit of revision for you.

CaCO3 CaO + CO2

If I heated 100g of calcium carbonate and had 56g of calcium oxide at the end, how much carbon dioxide did I make?

Can you explain why?

The second part of the limestone cycle

• When you react calcium oxide with water it makes calcium hydroxide. The reaction is highly exothermic and produces a lot of heat.

• The reaction has been used to heat self heating cans of hot drinks.

• Can you complete the following word equation?

Calcium oxide + water ______________

The third part of the limestone cycle

• When you blow carbon dioxide into limewater it makes calcium carbonate again. This turns the limewater cloudy.

• Can you complete the following word equation?

Calcium hydroxide + carbon dioxide __________ + water

Summary

State that limestone is mainly composed of the compound calcium carbonate, is quarried and can be used as a building material.

Describe how calcium carbonate can be decomposed by heating to make calcium oxide and carbon dioxide.

Explain the steps of the limestone cycle

Limestone and Building Materials

Other metal carbonates

What do I need to know?

MustRecall that when calcium carbonate (limestone) is heated it thermally decomposes.ShouldInvestigate the decomposition of other metal carbonatesCouldCompare the reactions of different metal carbonates with acids.

Thermal decomposition

Test your knowledge:

When calcium carbonate is _________ it thermally __________ to produce calcium oxide.

Other metal carbonates decompose on heating in a similar way to calcium _________.

Metal carbonate Metal ______ + ________

[HEATED, OXIDE, CARBONATE, DECOMPOSES, CARBON DIOXIDE]

Word equations

Write the word equations for the decomposition of the following carbonates:

• Magnesium carbonate (MgCO3)• Zinc carbonate (ZnCO3)• Copper carbonate (CuCO3)

If you are confident write the symbol equations too

Check your answers

Magnesium carbonate magnesium oxide + carbon dioxideMgCO3 MgO + CO2

Zinc carbonate zinc oxide + carbon dioxideZnCO3 ZnO + CO2

Copper carbonate copper oxide + carbon dioxideCuCO3 CuO + CO2

Acid rain and metal carbonates

• Metal carbonates react with acids.• The products are carbon dioxide, a salt and

water.• This means that limestone buildings erode

with acid rain.

Test your knowledge

Metal _________ react with ____ to produce ______ ______ a salt and water.

Limestone is __________ by acid rain.[CARBONATES, CARBON DIOXIDE, DAMAGED, ACID]

For example:Calcium carbonate + hydrochloric acid carbon dioxide + calcium chloride + water

Homework

In your book: Title: “Building Materials”

Find out and write down the composition (make up) of cement, concrete and mortar.

Give ONE or more uses for EACH

Summary

MustRecall that when calcium carbonate (limestone) is heated it thermally decomposes.ShouldInvestigate the decomposition of other metal carbonatesCouldCompare the reactions of different metal carbonates with acids.

Limestone and Building Materials

Cement, mortar and concrete

What do I need to know?

MustState that limestone is heated with clay to make cementShouldExplain that mixing cement with sand makes mortar and mixing cement with sand and aggregate makes concrete and uses for each of theseCouldDescribe the problems of producing cement and the effects of smoke particles from the fuel.

Building materials

1. What is the composition of:a) Cementb) Mortarc) Concrete

2. Give a different use for each

Cement, mortar and concrete

Cement powder + water = cement

Cement powder + water + sand = mortar

Cement powder + water + sand + aggregate = concrete

The facts – cement

Cement powder + water = cement

Strong but brittle May be used for fence postsUsually used as mortar or concrete

The facts – mortar

Cement powder + water + sand = mortar

Sand makes it flexible. Used as a filler between stone and for pointingNot very strong if hit with a hammer

The facts – concrete

Cement powder + water + sand + aggregate = concrete

Aggregate makes concrete strong.It can be used as foundations and paving slabs.

Sand content vs. aggregate content

• The more sand you add to mortar the WEAKER it becomes.

Anomalous results

• A result which does not follow the expected pattern

• Clue – work out the difference between each result to determine the odd one out.

Making cement• Cement is made by heating calcium carbonate

(limestone) in an oven (called a lime kiln) with clay. These are two types of lime kiln

What happens in a lime kiln?

• Methane gas is burned (like a Bunsen) to heat the limestone

• This produces CO2

• Calcium carbonate thermally decomposes • This produces CO2 and calcium oxide• Air is blown through to flush out the CO2 and

provide oxygen for the methane to burn• Nitrogen from the air is unreacted.

Choosing a fuel

• Burning different fuels at the limekiln may have a number of effects.

• It may be more efficient • It may cost less or be more cost effective• However, it may give rise to more dust or

particles and this may affect the amount of deposited smoke particles and the health of the local community.

Examination questions frequently examine the use of a different fuel at a cement works (limekiln). It considers in depth the problems of the smoke particles that can be produced.

In your answer you need to assess the evidence provided and consider concepts such as:

• Carrying out an independent scientific study• The idea of a fair test• Assessing data to determine whether it shows the whole picture.• The difference between particle size (measured in mm) and concentration

of particles (measured in ppm or parts per million).

The problem of smoke particles

Summary

MustState that limestone is heated with clay to make cementShouldExplain that mixing cement with sand makes mortar and mixing cement with sand and aggregate makes concrete and uses for each of theseCouldDescribe the problems of producing cement and the effects of smoke particles from the fuel.