AQA GCSE Chemistry 8462: Using resources – 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 Topic 10, Using resources (sections 4.10.1 to 4.10.4), of the AQA GCSE Chemistry (8462) specification, for teaching from September 2016 with GCSE exams from June 2018 (version 1.1). The topic is examined on Paper 2 at Foundation and Higher tier. Question 4 and parts 11(c) and 11(d) test Higher tier only content and are labelled; everything else suits both tiers.

Learn the content first in the study guide and the revision notes. The course hub is AQA GCSE Chemistry and the printable checklist lists every statement.

Questions

1. A water company supplies potable water from a lake.

(a) Explain the difference between potable water and pure water. [2] (b) Give the reason for passing the water through filter beds and the reason for sterilising it. [2]

2. A student analyses a sample of sea water. An empty evaporating basin has a mass of 41.62 g. She evaporates 25.0 cm³ of sea water to dryness in it. The basin and residue then have a mass of 42.50 g.

(a) Calculate the mass of dissolved solids in g/dm³. [3] (b) Describe how she could obtain pure water from the sea water and show that it is pure. [3]

3. A town produces sewage.

(a) Describe the main stages of sewage treatment. [4] (b) Comment on how easy it is to obtain potable water from ground water compared with salt water. [2]

4. (Higher tier only) A company has a large tip of waste rock containing 0.5% copper compounds.

(a) Describe how phytomining could be used to obtain copper compounds from the tip. [2] (b) Write a balanced symbol equation for obtaining copper from copper sulfate solution using scrap iron. [1] (c) Information: bioleaching the tip would take several years; it needs no new mine; leachate could pollute ground water if it escapes. Evaluate the use of bioleaching for this tip. [3]

5. The table shows data for making one shopping bag (illustrative values).

Bag	Energy (MJ)	Water (dm³)	Solid waste (g)
Plastic	0.9	0.2	7
Paper	2.7	1.4	50

A shopper makes 12 trips. Option 1: a new plastic bag each trip. Option 2: 4 paper bags, each used for 3 trips.

(a) Calculate the total energy for each option. [2] (b) Use the data to evaluate which option has the lower environmental impact. Include one factor not shown in the table. [4] (c) Explain why a life cycle assessment is not a purely objective process. [1]

6. A steelworks makes 1000 tonnes of steel. It uses 250 tonnes of scrap steel added to iron from a blast furnace.

(a) Calculate the percentage of the steel’s mass that came from scrap. [1] (b) Explain two benefits of using scrap steel. [2] (c) Suggest why reusing a glass bottle uses less energy than recycling it. [1]

7. A student sets up three test tubes, each with an iron nail. Tube A: tap water, open to the air. Tube B: boiled water with a layer of oil on top. Tube C: dry air with calcium chloride. After a week only the nail in A has rusted.

(a) Explain why the water in B was boiled and covered with oil. [2] (b) State the purpose of the calcium chloride in C. [1] (c) Write a conclusion for the experiment. [1]

8. Blocks of zinc are bolted to the steel hull of a ship.

(a) Explain how the zinc blocks stop the hull rusting. [3] (b) Explain why a painted hull can rust once the paint is scratched. [1]

9. This question is about alloys.

(a) A 9 carat gold ring has a mass of 4.8 g. Calculate the mass of gold in the ring. [2] (b) Give one use of bronze. [1] (c) The table shows three steels.

Steel	Composition	Property
P	Iron with 0.1% carbon	Soft, easily shaped
Q	Iron with 1.2% carbon	Strong, brittle
R	Iron with 18% chromium and 8% nickel	Hard, resists corrosion

Choose the best steel for (i) a kitchen sink and (ii) a car door panel. Give a reason for each. [2]

10. This question is about polymers and composites.

(a) Low density and high density poly(ethene) are both made from ethene. Explain why they have different properties. [2] (b) Explain why a thermosetting polymer is used for a saucepan handle, but a thermosoftening polymer is not. [3] (c) Name the two parts that make up most composites. [1]

11. Ammonia is made by the Haber process: N₂ + 3H₂ ⇌ 2NH₃

(a) Give the source of the nitrogen and the source of the hydrogen. [2] (b) Describe what happens to the gas mixture after it leaves the reactor. [2] (c) (Higher tier only) The forward reaction is exothermic. Explain why a temperature of about 450 °C is used. [3] (d) (Higher tier only) Explain why a pressure of about 200 atmospheres is used rather than a much higher pressure. [2]

12. Ammonium nitrate, NH₄NO₃, is used in NPK fertilisers.

(a) Calculate the percentage by mass of nitrogen in ammonium nitrate. (Aᵣ: N = 14, H = 1, O = 16) [2] (b) Phosphate rock is treated with nitric acid. Name the two products. [2] (c) Compare the industrial production of ammonium nitrate with its preparation in a school laboratory. [3]

Answers

1. (a) Potable water is safe to drink, with low levels of dissolved salts and microbes [1]. Pure water contains no dissolved substances, only water [1]. (b) Filter beds remove solid particles [1]; sterilising kills microbes [1]. Examiner insight: “Potable water is clean” does not score – you must say it still contains dissolved substances.

2. (a) Mass of solids = 42.50 − 41.62 = 0.88 g [1]; volume = 0.0250 dm³ [1]; 0.88 ÷ 0.0250 = 35.2 g/dm³ [1]. (b) Heat the sea water so the water boils [1]; condense the steam in a condenser and collect the distillate [1]; show it boils at 100 °C, or leaves no residue when evaporated [1]. Examiner insight: Forgetting to convert cm³ to dm³ gives 0.0352, which loses the last two marks; allow error carried forward from a wrong mass.

3. (a) Screening and grit removal [1]; sedimentation to form sludge and effluent [1]; anaerobic digestion of the sludge [1]; aerobic biological treatment of the effluent [1]. (b) Ground water only needs filtering and sterilising, so it is easier [1]; salt water needs desalination, which uses large amounts of energy [1]. Examiner insight: Swapping “aerobic” and “anaerobic” between sludge and effluent loses both of those marks.

4. (a) Grow plants on the tip; they absorb copper compounds [1]. Harvest and burn the plants; the ash contains copper compounds [1]. (b) Fe + CuSO₄ → FeSO₄ + Cu [1] (c) Advantage: no digging, moving or disposing of large amounts of rock, and it uses the low-grade ore [1]. Disadvantage: slow, and risk of ground water pollution [1]. Judgement, e.g. worthwhile if the leachate is contained, because copper ores are scarce [1]. Examiner insight: The third mark in (c) needs a judgement that follows from the points made; a list of pros and cons alone scores two.

5. (a) Option 1: 12 × 0.9 = 10.8 MJ [1]; Option 2: 4 × 2.7 = 10.8 MJ [1]. (b) Energy is the same for both options [1]. Option 1 uses less water: 2.4 dm³ vs 5.6 dm³ [1]. Option 1 makes less solid waste: 84 g vs 200 g [1]. Other factor, e.g. plastic comes from crude oil, a finite resource, while paper is renewable and biodegradable [1]. (c) Giving values to pollutant effects needs value judgements [1]. Examiner insight: Quote calculated figures from the data; “plastic is worse for the environment” with no numbers scores nothing.

6. (a) 250 ÷ 1000 × 100 = 25% [1] (b) Less iron ore needs to be mined, conserving a finite resource [1]; less energy is needed than extracting iron from ore [1]. (c) Reuse only needs washing; recycling needs crushing and melting at high temperature [1]. Examiner insight: Each benefit in (b) must be a different idea; “saves resources” twice scores one mark.

7. (a) Boiling removes dissolved air [1]; oil stops air dissolving back in [1]. (b) It absorbs water, keeping the air dry [1]. (c) Iron needs both air and water to rust [1]. Examiner insight: The conclusion must name both air and water; “iron needs water to rust” is not enough.

8. (a) Zinc is more reactive than iron [1], so zinc reacts with air and water instead [1]; this is sacrificial protection, and the zinc is used up while the steel stays intact [1]. (b) The scratch lets air and water reach the steel, so the barrier no longer works [1]. Examiner insight: “Zinc is a coating” scores nothing in (a); the marks depend on relative reactivity.

9. (a) Fraction of gold = 9/24 [1]; 9/24 × 4.8 = 1.8 g [1]. (b) Statues or medals [1]. (c) (i) R, because it resists corrosion in water [1]; (ii) P, because it is soft and easily shaped [1]. Examiner insight: A choice with no reason is not credited; each mark needs the steel and the matching property.

10. (a) They are made under different conditions (temperature, pressure, catalyst) [1], so their polymer chains differ in structure [1]. (b) Thermosetting polymers have cross-links between chains [1], so they do not melt when heated [1]. Thermosoftening polymers have no cross-links and melt when hot, so the handle would soften [1]. (c) A matrix (binder) and a reinforcement [1]. Examiner insight: “Stronger bonds” does not replace “cross-links”; use the structural term.

11. (a) Nitrogen from the air [1]; hydrogen from natural gas [1]. (b) It is cooled, so ammonia liquefies and is removed [1]; unreacted nitrogen and hydrogen are recycled [1]. (c) A lower temperature would give a higher yield, because the forward reaction is exothermic [1], but the rate would be too slow [1]. So 450 °C is a compromise between yield and rate [1]. (d) Higher pressure would increase yield and rate [1], but needs stronger equipment and more energy, so it costs more and is less safe [1]. Examiner insight: A “compromise” answer only scores if both sides – yield and rate, or yield and cost – are stated.

12. (a) Mr = 14 + 4 + 14 + 48 = 80 [1]; 28 ÷ 80 × 100 = 35.0% [1]. (b) Phosphoric acid [1] and calcium nitrate [1]. (c) Industry works on a large scale and continuously; the lab makes small batches [1]. Industry makes its ammonia and nitric acid in integrated processes on site; the lab uses bought solutions [1]. The lab uses titration and crystallisation with dilute solutions; industry uses concentrated reactants [1]. Examiner insight: Using 14 instead of 28 for nitrogen (NH₄NO₃ has two N atoms) gives 17.5% and loses the accuracy mark.

Where marks are usually lost

• Calling potable water “pure”.
• Not converting cm³ to dm³ in dissolved-solids calculations.
• Swapping aerobic and anaerobic in sewage treatment.
• Explaining galvanising as a barrier with no mention of reactivity.
• Rust conclusions that name only water or only oxygen.
• LCA answers with no figures from the data.
• Saying a catalyst increases the yield of ammonia.
• Counting only one nitrogen atom in ammonium nitrate.
• Choosing a material without linking a property to the use.

Next steps

• Using resources revision notes
• Using resources study guide
• Chemistry of the atmosphere practice questions
• AQA GCSE Chemistry course hub
• Printable checklist
• All free 10-minute diagnostics
• Book a free trial class

Official syllabus

AQA GCSE Chemistry (8462) specification, for teaching from September 2016, GCSE exams June 2018 onwards, version 1.1, published by AQA – section 4.10 Using resources.