1. States of matter

1.1 Solids, liquids and gases

1.2 Diffusion

2. Atoms, elements and compounds

2.1 Elements, compounds and mixtures

2.2 Atomic structure and the Periodic Table

2.3 Isotopes

2.4 Ions and ionic bonds

2.5 Simple molecules and covalent bonds

2.6 Giant covalent structures

2.7 Metallic bonding

3. Stoichiometry

3.1 Formulae

3.2 Relative masses of atoms and molecules

3.3 The mole and the Avogadro constant

4. Electrochemistry

4.1 Electrolysis

4.2 Hydrogen–oxygen fuel cells

5. Chemical energetics

5.1 Exothermic and endothermic reactions

6. Chemical reactions

6.1 Physical and chemical changes

6.2 Rate of reaction

6.3 Reversible reactions and equilibrium

6.4 Redox

7. Acids, bases and salts

7.1 The characteristic properties of acids and bases

7.2 Oxides

7.3 Preparation of salts

8. The Periodic Table

8.1 Arrangement of elements

8.2 Group I properties

8.3 Group VII properties

8.4 Transition elements

8.5 Noble gases

9. Metals

9.1 Properties of metals

9.2 Uses of metals

9.3 Alloys and their properties

9.4 Reactivity series

9.5 Corrosion of metals

9.6 Extraction of metals

10. Chemistry of the environment

10.1 Water

10.2 Fertilisers

10.3 Air quality and climate

11. Organic chemistry

11.1 Formulae, functional groups and terminology

11.2 Naming organic compounds

11.3 Fuels

11.4 Alkanes

11.5 Alkenes

11.6 Alcohols

11.7 Carboxylic acids

11.8 Polymers

12. Experimental techniques and chemical analysis

12.1 Experimental design

12.2 Acid–base titrations

12.3 Chromatography

12.4 Separation and purification

12.5 Identification of ions and gases

IGCSE Chemistry 6.4 Redox Question Bank

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

(a)

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.

[ 1 ]

(i)

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

[ 1 ]

[Maximum number: 3]

The diagram shows a blast furnace.

(a)

The following equations represent reactions which take place in the blast furnace.

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

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

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

D $\mathrm{CO}_{2}+\mathrm{C} \rightarrow 2 \mathrm{CO}$

E $\mathrm{Fe}_{2} \mathrm{O}_{3}+3 \mathrm{CO} \rightarrow 2 \mathrm{Fe}+3 \mathrm{CO}_{2}$

[ 1 ]

(i)

In which reaction is carbon both oxidised and reduced?

[ 1 ]

(b)

The graph shows how the malleability of iron changes as the percentage of carbon in the iron changes.

[ 2 ]

(i)

Iron obtained from the blast furnace contains high levels of carbon.

Explain how the amount of carbon in the iron can be decreased.

[ 2 ]

(a)

The symbols of the elements in Period 2 of the Periodic Table are shown.
Li Be
B
C
N
0
F
Ne

Use the symbols of the elements in Period 2 to answer the questions that follow. Each symbol may be used once, more than once or not at all.

Give the symbol of the element that:

[ 1 ]

(i)

only has an oxidation number of zero.

[ 1 ]

(a)

The symbols of the elements in Period 3 of the Periodic Table are shown.

Use the symbols of the elements in Period 3 to answer the questions that follow. Each symbol may be used once, more than once, or not at all.

Give the symbol of the element that:

[ 1 ]

(i)

has an oxidation number of -1 when it forms a compound with hydrogen.

[ 1 ]

(a)

Aluminium is extracted from its ore by electrolysis.

[ 1 ]

(i)

The reaction at the anode during the extraction of aluminium by electrolysis is shown.

2 \mathrm{O}^{2-} \rightarrow \mathrm{O}_{2}+4 \mathrm{e}^{-}

Is this process oxidation or reduction?
Give a reason for your answer.

[ 1 ]

[Maximum number: 1]

Three ionic compounds of vanadium have the formulae $\mathrm{V}_{2} \mathrm{O}, \mathrm{VCl}_{2}$ and $\mathrm{V}_{2} \mathrm{O}_{3}$ .
What is the charge on the vanadium ion in each compound?

$\mathrm{V}_{2} \mathrm{O}$

$\mathrm{VCl}_{2}$

$\mathrm{~V}_{2} \mathrm{O}_{3}$

-2

[Maximum number: 1]

The diagram shows a simple cell.

Which statement about the process occurring when the cell is in operation is correct?

$\mathrm{Cu}^{2+}$ ions are formed in solution.

Electrons travel through the solution.

C The reaction $\mathrm{Zn} \rightarrow \mathrm{Zn}^{2+}+2 \mathrm{e}^{-}$ occurs.

D The zinc electrode increases in mass.

[Maximum number: 2]

Ammonia is manufactured by the Haber process.

(a)

Ammonia, $\mathrm{NH}_{3}$ , is used to produce nitric acid, $\mathrm{HNO}_{3}$ . This happens in a three-stage process.

Stage 1 is a redox reaction.

4 \mathrm{NH}_{3}+5 \mathrm{O}_{2} \rightarrow 4 \mathrm{NO}+6 \mathrm{H}_{2} \mathrm{O}

[ 2 ]

(i)

Identify what is oxidised in stage 1.

Give a reason for your answer.
substance oxidised
reason

[ 2 ]

[Maximum number: 2]

Zinc is extracted from an ore containing zinc sulfide.

(a)

This ore is converted to zinc oxide, ZnO .

Zinc oxide is then reacted with carbon.

[ 2 ]

(i)

State what type of chemical change happens to the zinc in zinc oxide in this reaction.

Explain your answer.
chemical change
explanation

[ 2 ]

[Maximum number: 1]

The electrical energy, or voltage, of two simple cells is measured.

cell 1

cell 2

statement 1 The voltage of cell 1 is greater than cell 2.
statement 2 Zinc is more reactive than copper.
statement 3 Magnesium is oxidised in both cells.
statement 4 Magnesium atoms lose electrons to form magnesium ions.
Which option is correct?

All the statements are correct.

Only statements 1 and 3 are correct.

Statement 2 is correct and explains statement 1.

Statement 4 is correct and explains statement 3.

0 selected

Question 1

Question 1(b)

Question 1(b)(v)

Question 1

Question 1(a)

Question 1(a)(iii)

Question 1(c)

Question 1(c)(ii)

Question 2

Question 2(a)

Question 2(a)(vi)

Question 2

Question 2(a)

Question 2(a)(vi)

Question 2

Question 2(b)

Question 2(b)(iv)

Question 9

Question 12

Question 2

Question 2(d)

Question 2(d)(i)

Question 2

Question 2(b)

Question 2(b)(ii)

Question 13