CIE iGCSE Co-Ordinated Science C9.6 Extraction of metals Exam Style Questions Paper 3
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic C9.6 — Extraction of metals (Part (a))
• Topic C9.5 — Corrosion of metals (Part (b))
• Topic C9.1 — Properties of metals (Part (c)(i))
• Topic C7.1 — The characteristic properties of acids and bases (Part (c)(ii))
• Topic C9.1 — Properties of metals (Part (d))
▶️ Answer/Explanation
(a)(i) Reduction is the loss of oxygen from a substance.
In the blast furnace, iron(III) oxide is reduced by carbon monoxide to produce iron metal. The iron(III) oxide loses oxygen to become iron.
(a)(ii) Hematite
Hematite is the main ore of iron used in the blast furnace. Its chemical formula is Fe₂O₃ (iron(III) oxide).
(b) oxygen and water
Rusting of iron requires both oxygen (from the air) and water to be present. If either is absent, rusting does not occur.
(c)(i) Iron forms a coloured compound (pale green iron(II) chloride).
Transition metals are characterised by forming coloured compounds. The pale green colour of iron(II) chloride indicates that iron is a transition metal.
(c)(ii) Fe(s) + 2HCl(aq) → FeCl₂(aq) + H₂(g)
The equation is balanced with 2 moles of HCl reacting with 1 mole of iron. The state symbols are: (s) for solid iron, (aq) for aqueous hydrochloric acid and iron(II) chloride, and (g) for hydrogen gas.
(d) High melting/boiling point / malleable / ductile
Most metals have characteristic physical properties including high melting and boiling points, malleability (can be hammered into shapes), and ductility (can be drawn into wires). Any one of these is correct.
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic C9.6 — Extraction of metals (Part (a)(i))
• Topic C8.2 — Group I properties (Part (a)(ii))
• Topic C9.1 — Properties of metals (Part (a)(iii))
• Topic C4.1 — Electrolysis (Part (a)(iv))
• Topic C7.1 — Characteristic properties of acids (Parts (b)(i), (b)(ii), (b)(iii))
• Topic C9.4 — Reactivity series (Part (b)(iii))
▶️ Answer/Explanation
(a)(i) aluminium
Bauxite is the main ore of aluminium. Aluminium is extracted from bauxite by electrolysis because it is a reactive metal.
(a)(ii) sodium
Sodium is an alkali metal found in Group I of the Periodic Table. The other alkali metals include lithium and potassium.
(a)(iii) iron
Steel is an alloy made primarily of iron with small amounts of carbon and other elements such as chromium and nickel.
(a)(iv) platinum
Platinum is used as an inert electrode in electrolysis because it is unreactive and does not participate in the reaction.
(b)(i) magnesium chloride / hydrogen
The products of the reaction between magnesium and hydrochloric acid are magnesium chloride (a salt) and hydrogen gas.
(b)(ii) effect on rate of reaction: increases
Explanation: The concentration of the acid has doubled from \(36.5 \, \text{g/dm}^3\) to \(73.0 \, \text{g/dm}^3\). Increasing the concentration means there are more reactant particles per unit volume. This leads to a higher frequency of successful collisions between magnesium atoms and hydrogen ions, thereby increasing the rate of reaction.
(b)(iii) calcium / sodium / potassium
Calcium, sodium and potassium are all more reactive than magnesium in the reactivity series. These metals react more vigorously with dilute acids and water compared to magnesium.