Limestone (WJEC GCSE Chemistry)

The following diagram shows how limestone, CaCO₃, can be converted into useful products.

When a piece of limestone is heated strongly its mass decreases.

State the type of reaction taking place.

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[2]

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A student investigated the decomposition of three different metal carbonates.

She measured the time taken for limewater to turn milky using the following apparatus.

Three samples of each metal carbonate were tested. Her results are shown in the table.

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Mean time = ........................................... s

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Most stable ..............................................................................

          ..............................................................................

Least stable ..............................................................................

Reason  ..............................................................................

II.     Explain the order of stability of the carbonates.

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CuCO₃  .............................. + ..............................  

Calculate the relative formula mass, M_r, of copper(II) carbonate, CuCO₃.

A_r(C) = 12          A_r(O) = 16          A_r(Cu) = 63.5

M_r = ...........................................

The flow chart shows the stages a student carried out to change calcium carbonate (limestone) into calcium hydroxide solution (limewater).

Use the information in the flow chart to answer parts (i) to (iii).

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The student blew gently through a straw placed in a test tube containing limewater.

Describe what you would expect to happen to the limewater. Give a reason for your answer.

Observation ....................................................................................................

Reason ....................................................................................................

Quicklime is manufactured from limestone in a lime kiln. A manufacturer expected to obtain 5.6 tonnes per 10 tonnes of limestone used. The actual mass of quicklime produced was 5.1 tonnes.

Calculate the percentage yield of quicklime for this manufacturing process.

percentage yield = ..................................... %

Limestone quarrying is an important business in the UK. Quarrying creates jobs in areas where there are often limited opportunities. There is a huge demand for the products of quarrying, such as building stone and cement. Good roads and rail links are needed for transporting the products of quarrying. Thousands of people are employed in quarrying and related industries.

Many people argue against the opening of a quarry in their area despite all the benefits of limestone quarrying. Explain two reasons local people might use in an attempt to stop the opening of a new quarry in their area. 

When limestone is heated in a lime kiln thermal decomposition takes place.

Write a balanced symbol equation for this reaction

Higher Tier Only

Calcium silicide is a compound containing calcium and silicon only. A sample of calcium silicide was found to contain 2.0 g of calcium and 2.8 g of silicon.

Calculate the simplest formula for this compound. You must show your working. 

A small piece of limestone, which contains calcium carbonate, was heated strongly for about 10 minutes using a Bunsen burner flame as shown in the diagram.

During the reaction calcium oxide was formed.

Give the common name of calcium oxide.

The calcium oxide was allowed to cool and cold water was added dropwise as shown.

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........................................ + ........................................  ........................................

When samples of calcium carbonate and copper(II) carbonate are heated they undergo thermal decomposition.

Describe one similarity and one difference in the reactions that take place when these two carbonates thermally decompose.

Give the balanced symbol equation for the reaction that takes place when calcium carbonate is heated.

.............................. → .............................. + ..............................

If the two carbonates were replaced with sodium carbonate, what would be the difference when this was heated? Give a reason for this difference.

The table below shows information about three substances. Complete the table.

A group of pupils investigated the composition of egg shells. They suspected that egg shells contain calcium carbonate. They carried out the following tests.

Choose from the box below the colour you would expect to see if egg shells contain calcium ions.

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Colour ..............................................................

Name the gas formed if egg shells contain carbonate ions. Describe the test you would carry out to identify this gas. Include the result for your test.

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Gas ............................................................................................

Test and result ..............................................................................................................................................................

Calculate the percentage of calcium carbonate in these egg shells.

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The box below shows some of the concerns a local conservation group have about the opening of a new limestone quarry in their area.

The quarry owner suggests that planting trees around the quarry will reduce the impact of noise pollution. Suggest two other things the quarry owner could do to reduce the impact of the quarry on the local environment.

Suggest two advantages of limestone quarrying.

Advantage 1 ..................................

Advantage 2 ..................................

Limestone is an important raw material. It can be used as a building material or converted into quicklime and slaked lime.

Describe and explain the sequence of reactions carried out in the laboratory to convert limestone into slaked lime.

The following table shows the decomposition temperatures of Group 2 metal carbonates and nitrates.

Describe the trends in the stabilities of the Group 2 carbonates and nitrates.

When a carbonate decomposes it produces carbon dioxide gas. Describe an experiment that could be carried out to show that carbon dioxide gas is produced during the reaction.

When calcium nitrate decomposes it forms calcium oxide, oxygen and nitrogen dioxide, NO₂.

Write a symbol equation for the reaction.

Limestone, CaCO₃, is an important raw material. It can be converted into other useful materials as shown in the diagram below.

Describe how these reactions can be carried out in a laboratory.

Your answer should include:

• the conditions required for each reaction;
• observations at each stage;
• equations for the reactions taking place.

When metal carbonates are heated they can thermally decompose. 

During the decomposition carbon dioxide gas is given off.

A student investigated the time taken for carbon dioxide to be given off when different metal carbonates were heated. The diagram shows the apparatus she used.

She timed how long it took for the limewater to start to turn cloudy.

The table shows her results.

Using the students results to deduce the order of increasing reactivity of the metals present in the metal carbonate. Explain your answer.

State two variables that must be kept the same during the investigation.

Higher tier only

The student used 3.04 g of barium carbonate. Assuming all of the barium carbonate had decomposed, calculate the volume, in cm³, of carbon dioxide formed in the reaction. 

A_r(Ba) = 137             A_r(C) = 12              A_r(O) = 16

When calcium carbonate is heated it forms calcium oxide. Droplets of water are then added to form sparingly soluble calcium hydroxide.

State the ionic equation for the formation of solid calcium hydroxide.

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Draw a completed energy profile for the reaction between water and calcium oxide.

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A student made a solution of calcium hydroxide solution and added universal indicator solution. The solution turned blue.

Explain why.

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