Pearson Edexcel International GCSE Chemistry 4CH1: Extraction and uses of metals – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions cover sub-topic 2(e) Extraction and uses of metals of the Pearson Edexcel International GCSE Chemistry (4CH1) specification, Issue 3 (September 2024): statements 2.22C–2.27C. The qualification is untiered. Every statement in this sub-topic has a C reference, so all of it is Paper 2 only. Course links: 4CH1 Chemistry hub, printable checklist, the extraction and uses of metals study guide and the extraction and uses of metals revision notes. For the reactivity series and rusting, use the reactivity practice and inorganic chemistry practice.

Relative atomic masses: Na = 23, C = 12, O = 16, Al = 27, Cl = 35.5, Fe = 56, Zn = 65.

Questions

1. Metals are obtained from the Earth’s crust.

(a) State what is meant by an ore. [1] (b) Explain why gold is found as the uncombined element. [1]

2. Mild steel is an alloy.

(a) State what is meant by an alloy. [1] (b) Name the non-metal element that is mixed with iron in mild steel. [1]

3. Carbon lies between aluminium and zinc in the reactivity series. Lead lies between iron and copper.

For each metal, state how it is extracted from its oxide and give a reason.

(a) magnesium [2] (b) lead [2]

4. Copper is used for electrical wiring and for water pipes in houses. Explain why copper is suitable for:

(a) electrical wiring [2] (b) water pipes [2]

5. Zinc is extracted by heating zinc oxide with carbon.

ZnO + C → Zn + CO

(a) Identify the substance that is reduced. Explain your answer in terms of oxygen. [2] (b) Identify the reducing agent. [1] (c) Calculate the maximum mass of zinc that can be obtained from 8.10 tonnes of zinc oxide. [3] (d) A works obtains 5.85 tonnes of zinc from 8.10 tonnes of zinc oxide. Calculate the percentage yield. [2]

6. Choose low-carbon (mild) steel, high-carbon steel or stainless steel for each object. Give a property that explains each choice.

(a) a car door panel, which is pressed into a curved shape [2] (b) the cutting blade of a wood chisel [2] (c) a set of surgical instruments that are washed many times [2]

7. Aircraft bodies are made from an alloy of aluminium containing small amounts of copper and magnesium.

(a) Explain why the alloy is harder than pure aluminium. [3] (b) Give two properties of aluminium, other than hardness, that make its alloys suitable for aircraft. [2]

8. Aluminium is extracted by electrolysis of aluminium oxide. The electrodes are made of graphite.

(a) Explain why aluminium cannot be extracted by heating aluminium oxide with carbon. [2] (b) Explain why the aluminium oxide is dissolved in molten cryolite. [2] (c) Explain why the positive electrodes must be replaced regularly. [2] (d) An ore contains 51.0% aluminium oxide, Al₂O₃, by mass. Calculate the maximum mass of aluminium that can be extracted from 200 tonnes of this ore. [3] (e) Making aluminium from its oxide uses about 15 kWh of electrical energy per kilogram. Recycling aluminium uses about 5% of this energy. Calculate the energy saved if your answer to (d) were made by recycling instead. [2]

9. Read this information about the extraction of sodium.

Sodium is extracted by electrolysis of molten sodium chloride. Calcium chloride is added, so the mixture is molten at about 600 °C instead of 801 °C. The anode is carbon and the cathode is iron. The sodium and chlorine formed are directed into separate chambers. 2NaCl → 2Na + Cl₂

(a) Use the reactivity series to explain why sodium is extracted by electrolysis. [2] (b) Suggest why calcium chloride is added. [2] (c) Suggest why the sodium and chlorine must be kept apart. [1] (d) Calculate the mass of chlorine formed when 230 kg of sodium is produced. [3]

10. An engineer is choosing a metal for overhead power cables. The table gives data for four metals, A to D.

Metal	Density in g/cm³	Electrical conductivity (copper = 100)	Corrosion in air	Cost
A	8.9	100	very slow	high
B	2.7	61	none (protective oxide layer)	medium
C	7.9	17	rusts	low
D	10.5	106	none	very high

Use the data to choose the most suitable metal. Justify your choice by comparing it with the other metals. [4]

11. In the blast furnace, coke burns to form carbon dioxide. The carbon dioxide reacts with more coke to form carbon monoxide, which reduces iron(III) oxide to iron.

(a) Write a balanced equation for the reaction of carbon dioxide with carbon. [1] (b) Explain why iron can be extracted using carbon but magnesium cannot. [2] (c) Calculate the percentage by mass of iron in iron(III) oxide, Fe₂O₃. [2] (d) Iron from the blast furnace contains about 4% carbon. Explain why most of it is made into steel rather than used directly. [1] (e) Suggest one environmental problem caused by extracting iron in this way. [1]

Answers

1. (a) A rock containing enough of a metal compound to make extracting the metal worthwhile [1]. (b) Gold is very unreactive, so it does not react with substances in the Earth’s crust [1]. Examiner insight: In (a), “a rock containing metal” without the idea of extraction being worthwhile does not describe an ore and would not score.

2. (a) A mixture of a metal with one or more other elements (usually other metals or carbon) [1]. (b) Carbon [1]. Examiner insight: “A compound of two metals” contradicts the definition: an alloy is a mixture, so this answer scores zero.

3. (a) Electrolysis of a molten compound [1], because magnesium is more reactive than carbon, so carbon cannot remove the oxygen [1]. (b) Heating the oxide with carbon [1], because lead is less reactive than carbon, so carbon can remove the oxygen [1]. Examiner insight: The reason mark needs a comparison with carbon; “magnesium is very reactive” on its own does not score the second mark.

4. (a) Copper is a very good conductor of electricity [1]. It is ductile, so it can be drawn into wires [1]. (b) Copper does not react with water, so the pipes do not corrode [1]. It can be bent into shape to fit around a building [1]. Examiner insight: Each mark needs a property; in (b), “it is unreactive” without linking it to water or corrosion is usually too vague for credit.

5. (a) Zinc oxide [1], because it loses oxygen [1]. (b) Carbon [1]. (c) Mr(ZnO) = 65 + 16 = 81 [1]. Mass of Zn = 8.10 × 65/81 [1] = 6.50 tonnes [1]. (d) Percentage yield = 5.85/6.50 × 100 [1] = 90.0% [1]. Examiner insight: “Zinc is reduced” scores zero in (a): zinc is the product, and it is the zinc oxide that loses oxygen. Error carried forward from (c) is allowed in (d).

6. (a) Low-carbon (mild) steel [1]: it is malleable, so it can be pressed into shape [1]. (b) High-carbon steel [1]: it is very hard, so it keeps a sharp edge [1]. (c) Stainless steel [1]: it resists corrosion, so it does not rust when washed [1]. Examiner insight: A correct property attached to the wrong steel is not credited.

7. (a) Copper and magnesium atoms are a different size from aluminium atoms [1]. They distort the regular layers of aluminium atoms [1], so the layers cannot slide over each other as easily [1]. (b) Low density [1]. Resists corrosion, because of a protective oxide layer [1]. Examiner insight: “Light” is not accepted in place of “low density”, and in (a) “atoms get in the way” without mentioning the layers misses the last two marks.

8. (a) Aluminium is more reactive than carbon [1], so carbon cannot remove oxygen from aluminium oxide [1]. (b) Aluminium oxide has a very high melting point [1]. Dissolving it in cryolite lets electrolysis take place at a lower temperature, which saves energy [1]. (c) Oxygen forms at the positive electrodes [1]. At the high temperature it reacts with the carbon, forming carbon dioxide, so the electrodes burn away [1]. (d) Mass of Al₂O₃ = 0.510 × 200 = 102 tonnes [1]. Mr(Al₂O₃) = 2(27) + 3(16) = 102, containing 54 of aluminium [1]. Mass of Al = 102 × 54/102 = 54.0 tonnes [1]. (e) Energy from oxide = 54 000 kg × 15 = 810 000 kWh [1]. Energy saved = 0.95 × 810 000 = 769 500 kWh (accept 770 000 kWh) [1]. Examiner insight: In (c), “the electrodes wear out” scores nothing; you need oxygen reacting with carbon. In (e), forgetting to convert tonnes to kilograms loses the first mark, with the second available by error carried forward.

9. (a) Sodium is more reactive than carbon [1], so carbon cannot reduce sodium compounds and electrolysis is needed [1]. (b) It lowers the melting point of the electrolyte [1], so less energy is needed to keep it molten, which reduces cost [1]. (c) They would react together, forming sodium chloride again [1]. (d) Moles of Na = 230 000/23 = 10 000 mol [1]. Moles of Cl₂ = 10 000/2 = 5000 mol [1]. Mass of Cl₂ = 5000 × 71 = 355 000 g = 355 kg [1]. Examiner insight: In (b), “to lower the melting point” earns one mark; the second needs the consequence (energy or cost). Using 35.5 instead of 71 for Cl₂ in (d) gives 177.5 kg and loses the last mark.

10. Metal B [1]. It has the lowest density, so cables are lighter and need fewer or lighter supports than A, C or D [1]. Its conductivity is good, much higher than C [1]. It does not corrode, unlike C, and costs less than A and D [1]. Examiner insight: Justification marks need comparisons; quoting “density 2.7” without saying it is the lowest may not score.

11. (a) C + CO₂ → 2CO [1]. (b) Iron is less reactive than carbon, so carbon can remove oxygen from iron oxide [1]. Magnesium is more reactive than carbon, so carbon cannot remove oxygen from magnesium oxide [1]. (c) Mr(Fe₂O₃) = 2(56) + 3(16) = 160 [1]. % Fe = 112/160 × 100 = 70.0% [1]. (d) The carbon makes it brittle, so steel (with less carbon, or other added metals) is more useful [1]. (e) Carbon dioxide is released, a greenhouse gas that may contribute to climate change [1]. (Allow: mining damages land.) Examiner insight: In (b), each half needs both metals compared with carbon; “magnesium is too reactive” with no reference to carbon gains only one of the two marks.

Where marks are usually lost

• Naming the metal as reduced instead of the metal oxide.
• Giving the method of extraction but no comparison with carbon.
• Saying anodes “wear out” without explaining that oxygen reacts with carbon to form carbon dioxide.
• Missing the consequence (lower temperature, less energy, lower cost) when explaining why something is added.
• Giving a use, or a property, without linking the two.
• Writing “light” instead of “low density”, or “strong” when the question asks for another property.
• Leaving out “different-sized atoms” in the alloy explanation.
• Using Ar of chlorine (35.5) instead of Mr of Cl₂ (71).

Next steps

• Recap with the extraction and uses of metals revision notes.
• Rework anything you missed with the extraction and uses of metals study guide.
• Course hub: 4CH1 Chemistry and the printable checklist.
• Take the free all-topics diagnostic.
• Book a free trial class.

Official syllabus

Pearson Edexcel International GCSE in Chemistry (4CH1), Specification, Issue 3, September 2024, published by Pearson Education Limited. Topic 2: Inorganic chemistry, sub-topic (e) Extraction and uses of metals, statements 2.22C–2.27C.