CHEMICALS IN ACTION

Thermal Decomposition Reactions

Learning objectives

To know what is meant by a “thermal decomposition”

To recognise what happens during the thermal decomposition of limestone

Understand the thermal decomposition of limestone.

Know how limestone is made

Thermal Decomposition Reactions

A thermal decomposition occurs when a compound undergoes a reaction when it is heated.No other substance is involved in the reaction.

Thermal decomposition of copper carbonate

If heated copper carbonate will undergo a thermal decomposition.

Thermal decomposition of copper carbonate

The copper carbonate reacts when heated with no additional chemicals involved.

CuCO3(s) heat

CuO(s) + CO2(g)

Limestone

Chemistry text p46

Uses of limestone

Thermal decomposition of limestone

Carry out the practical outlined on the worksheet.

If you do not heat the limestone long enough you will not get any of the expected results

Reactions you need to know by heart!

Thermal decomposition of limestone (calcium carbonate)

calcium carbonate calcium oxide + carbon dioxide

CaCO3(s) CaO(s) + CO2(g)

Calcium oxide + water calcium hydroxide

CaO(s) + H2O(l) Ca(OH)2(aq)

Calcium hydroxide + carbon dioxide

calcium carbonate + water

Ca(OH)2(aq) + CO2(g) CaCO3(s) + H2O(l)

Information on limestone and its products

Read p48 of the Chemistry text.

Make a set of bullet points on “The manufacture of calcium hydroxide – slaked lime”.

Learning objectives

To know what is meant by a “thermal decomposition”

To recognise what happens during the thermal decomposition of limestone

Understand the thermal decomposition of limestone.

Know how limestone is made