Home / iGCSE Chemistry 0620 Extended – 9.6 Extraction of metals- Exam Style Questions Paper 4

iGCSE Chemistry 0620 Extended - 9.6 Extraction of metals- Exam Style Questions Paper 4- New Syllabus

iGCSE Chemistry Theory (Extended) Paper 4 - All Chapters

Question

(a) Iron is extracted from iron ore in a blast furnace. The iron compound in the main iron ore used in the blast furnace is iron(III) oxide.
(i) State the name of the main iron ore used in the blast furnace.
(ii) State how the main source of heat is provided in the blast furnace.
(iii) Name the gaseous reducing agent in the blast furnace.
(iv) Write a symbol equation for the reduction of iron(III) oxide by the gaseous reducing agent in (a)(iii).
(v) The main impurity in iron ore is silicon(IV) oxide. Write two symbol equations to show the role of limestone in removing silicon(IV) oxide from iron ore.
(b) Table 2.1 shows four different isotopes of iron, A, B, C and D.
Explain why they are isotopes of iron.
(c) Iron can form two different ions, $Fe^{2+}$ and $Fe^{3+}$.
(i) Complete Table 2.2 to show the number of protons, neutrons and electrons in the two iron ions shown.
(ii) Describe a test for aqueous $Fe^{2+}$ ions. Provide the test and the observations.
(d) An oxidising agent converts $Fe^{2+}$ ions to $Fe^{3+}$ ions.
(i) Define the term oxidising agent.
(ii) Explain why the conversion of $Fe^{2+}$ ions to $Fe^{3+}$ ions is described as oxidation.
(iii) The oxidising agent for the conversion of $Fe^{2+}$ ions to $Fe^{3+}$ ions is aqueous potassium manganate(VII). State one condition needed for the oxidation to take place.
(e) Iodide ions, $I^{-}$, reduce $Fe^{3+}$ ions to $Fe^{2+}$ ions in aqueous solution.
Suggest the identity of the other product formed in this reaction.

Most-appropriate topic codes (Cambridge IGCSE Chemistry 0620):

• Topic 9.6 — Extraction of metals
• Topic 2.3 — Isotopes
• Topic 6.4 — Redox

▶️ Answer/Explanation

(a)(i) Hematite.

(a)(ii) Burning of carbon (coke) in oxygen. (Explanation: The combustion of carbon, $C + O_{2} \rightarrow CO_{2}$, is a highly exothermic reaction that maintains the extreme temperatures required).

(a)(iii) Carbon monoxide ($CO$).

(a)(iv) $3CO + Fe_{2}O_{3} \rightarrow 2Fe + 3CO_{2}$

(a)(v)
1. $CaCO_{3} \rightarrow CaO + CO_{2}$ (Thermal decomposition of limestone yields basic calcium oxide).
2. $CaO + SiO_{2} \rightarrow CaSiO_{3}$ (The basic $CaO$ neutralizes the acidic silicon(IV) oxide impurity to form molten slag, calcium silicate).

(b) Isotopes are atoms of the same element that have the same number of protons (which makes them all Iron) but different numbers of neutrons (which gives them different mass numbers).

(c)(i)
For ${}^{54}Fe^{2+}$: Protons = 26, Neutrons = ($54 – 26$) = 28, Electrons = ($26 – 2$) = 24.
For ${}^{58}Fe^{3+}$: Protons = 26, Neutrons = ($58 – 26$) = 32, Electrons = ($26 – 3$) = 23.
Explanation: The atomic number of Iron ($Fe$) from the Periodic Table is 26. Protons = 26. Neutrons = Mass Number – Atomic Number. Electrons = Protons – Charge.

(c)(ii)
Test: Add aqueous sodium hydroxide ($NaOH(aq)$) or aqueous ammonia ($NH_{3}(aq)$).
Observations: A green precipitate is formed (which is insoluble in excess). (Note: It slowly turns brown at the surface as it oxidises in air to iron(III) hydroxide).

(d)(i) An oxidising agent is a substance that oxidises another substance and is itself reduced in the reaction.

(d)(ii) Oxidation is defined as the loss of electrons. The $Fe^{2+}$ ion loses one electron to become a more positively charged $Fe^{3+}$ ion.

(d)(iii) The reaction must be acidified. (Potassium manganate(VII) requires acidic conditions to function effectively as an oxidising agent, usually provided by dilute sulfuric acid).

(e) Iodine ($I_{2}$).
Explanation: When iodide ions ($I^{-}$) act as a reducing agent, they are themselves oxidized. Losing electrons converts the iodide ions into elemental iodine molecules: $2I^{-} \rightarrow I_{2} + 2e^{-}$.

More iGCSE Chemistry Paper 4 Questions.......
Scroll to Top