CAIE IGCSE Chemistry Oxidation and Reduction in Redox Reactions

Practise identifying the oxidised and reduced substances in equations by tracking oxygen, electrons or oxidation-number changes and giving the matching reason.

Exam points

name the substance oxidised and justify it by oxygen gain, electron loss or oxidation-number rise
name the substance reduced and justify it by oxygen loss, electron gain or oxidation-number fall
check both changes occur in the same equation and do not label unchanged spectator species

[Maximum number: 1]

Iron ore contains iron(III) oxide, $\mathrm{Fe}_{2} \mathrm{O}_{3}$ . A blast furnace is used to extract iron from $\mathrm{Fe}_{2} \mathrm{O}_{3}$ .
Equations for some of the reactions in the blast furnace are shown.

$equation $1 \mathrm{C}+\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}$$

$equation $2 \mathrm{CaCO}_{3} \rightarrow \mathrm{CaO}+\mathrm{CO}_{2}$$

$equation $3 \quad \mathrm{CaO}+\mathrm{SiO}_{2} \rightarrow \mathrm{CaSiO}_{3}$$

Iron(III) oxide, $\mathrm{Fe}_{2} \mathrm{O}_{3}$ , in iron ore is converted to iron when it reacts with carbon monoxide, CO , in the blast furnace.

Name the chemical process which happens to iron when iron(III) oxide is converted to iron in the blast furnace.

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6.4.5—Oxidation and reduction in redox question 1