Formula mass and empirical formulae: Edexcel GCSE Chemistry questions

Every Edexcel GCSE Chemistry exam question on Formula mass and empirical formulae (specification points 1.43–1.46), 2018–2025, with its mark scheme and examiner’s report.

All 64 questions on Formula mass and empirical formulae, as a list

June 2025, Paper 1 Higher, Q8(b)(i) (3 marks): Calculate the percentage by mass of oxygen in magnesium sulfate, MgSO4. (relative atomic mass: O = 16.0 relative formula mass: MgSO4 = 120) Give your answer to
June 2025, Paper 1 Foundation, Q4(c)(i) (2 marks): The formula of zinc nitrate is Zn(NO3)2 Calculate the relative formula mass of zinc nitrate, Zn(NO3)2 (relative atomic masses: Zn = 65, N = 14, O = 16) (2) rela
June 2025, Paper 1 Foundation, Q6(b) (2 marks): 25 000 kg of an ore of iron was found to contain 10 050 kg of iron. Calculate the percentage of iron in this ore of iron. mass of metal percentage of metal = ma
June 2025, Paper 2 Higher, Q1(b)(i) (1 mark): What is the formula of this molecule? (1) A C6H5(NO2)3 B C6H2(CH3)(3NO2) C C7H5N3O6 D C7H6N3O6
June 2025, Paper 2 Higher, Q3(c) (3 marks): One compound in crude oil contains 0.96 g of carbon atoms combined with 0.32 g of hydrogen atoms. Calculate the empirical formula of this compound. (relative at
June 2025, Paper 2 Higher, Q4(a)(i) (1 mark): What is the relative formula mass of propene? (relative atomic masses: C = 12, H = 1) (1) A 9 B 39 C 42 D 75
June 2025, Paper 2 Foundation, Q4(a)(ii) (1 mark): What is the empirical formula of compound B? (1) A CH3C(CH2)CH3 B C4H8 C CH4 D CH2
June 2025, Paper 2 Foundation, Q6(b)(v) (3 marks): Calculate the percentage by mass of hydrogen in lithium hydroxide, LiOH. relative atomic mass of element % by mass of element = relative formula mass of compoun
June 2025, Paper 2 Foundation, Q9(c) (3 marks): One compound in crude oil contains 0.96 g of carbon atoms combined with 0.32 g of hydrogen atoms. Calculate the empirical formula of this compound. (relative at
June 2025, Paper 2 Foundation, Q10(a)(i) (1 mark): What is the relative formula mass of propene? (relative atomic masses: C = 12, H = 1) (1) A 9 B 39 C 42 D 75
June 2024, Paper 1 Higher, Q3(b) (3 marks): Calculate the percentage by mass of sodium in sodium carbonate, Na2CO3. percentage by mass of element = total relative atomic mass of element relative formula m
June 2024, Paper 1 Foundation, Q5(b) (3 marks): Chlorine reacts with silicon to form silicon chloride. A sample of silicon chloride contains 1.4 g of silicon atoms and 7.1 g of chlorine atoms. Calculate the e
June 2024, Paper 1 Foundation, Q9(b) (3 marks): Calculate the percentage by mass of sodium in sodium carbonate, Na2CO3. percentage by mass of element = total relative atomic mass of element relative formula m
June 2024, Paper 2 Higher, Q4(c) (2 marks): The carbonate of element X has the formula X2CO3 . The relative formula mass of this carbonate is 230. Using this information, calculate the relative atomic mas
June 2024, Paper 2 Foundation, Q6(d) (3 marks): Potassium bromide contains 32.8% potassium by mass. Calculate the mass of potassium and the mass of bromine in 500 g potassium bromide. (3) mass of potassium =
June 2024, Paper 2 Foundation, Q10(c) (2 marks): The carbonate of element X has the formula X2CO3 . The relative formula mass of this carbonate is 230. Using this information, calculate the relative atomic mas
June 2023, Paper 1 Higher, Q9(a)(i) (1 mark): Use Figure 11 to deduce the empirical formula of compound S. (1)
June 2023, Paper 1 Foundation, Q4(b) (2 marks): Rust can be removed from steel by treating it with dilute hydrochloric acid. One product formed in this reaction is iron chloride, FeCl3. Calculate the relative
June 2023, Paper 1 Foundation, Q6(c) (3 marks): 1.20 g of magnesium reacts completely with 3.55 g of chlorine to form magnesium chloride. Calculate the empirical formula of the magnesium chloride. (relative a
June 2023, Paper 2 Higher, Q8(a) (1 mark): What is the percentage by mass of nitrogen in ammonia, NH3? (relative atomic masses: H = 1.0, N = 14) (1) A 18% B 42% C 51% D 82%
June 2023, Paper 2 Foundation, Q7(b)(ii) (1 mark): Using the information in Figure 13, give the empirical formula of hexane. (1)
June 2022, Paper 1 Higher, Q3(b) (3 marks): Calculate the percentage by mass of magnesium in magnesium carbonate, MgCO3. (relative atomic masses: C = 12.0, O = 16.0, Mg = 24.0) (3) percentage by mass of m
June 2022, Paper 1 Foundation, Q5(b) (3 marks): Aluminium reacts with bromine to form aluminium bromide. A sample of aluminium bromide contains 1.35 g of aluminium atoms and 12.00 g of bromine atoms. Calculat
June 2022, Paper 1 Foundation, Q9(b) (3 marks): Calculate the percentage by mass of magnesium in magnesium carbonate, MgCO3. (relative atomic masses: C = 12.0, O = 16.0, Mg = 24.0) (3) percentage by mass of m
June 2022, Paper 2 Higher, Q7(c) (4 marks): In another experiment, it was found that 1.24 g of phosphorus reacted completely with 1.60 g of oxygen to form phosphorus oxide. The relative formula mass of th
June 2022, Paper 2 Foundation, Q5(a)(iii) (1 mark): What is the relative formula mass of the compound in Figure 8? (relative atomic masses: H = 1.0, C = 12) (1) A 13 B 42 C 44 D 96
June 2022, Paper 2 Foundation, Q6(b)(iii) (3 marks): 34.4 % of the mass of iron chloride is iron. Calculate the mass of iron and the mass of chlorine in 125 g of iron chloride. (3) mass of iron = g mass of chlorin
November 2021, Paper 1 Higher, Q2(b) (2 marks): Dalton also investigated different gases. One of the gases that Dalton investigated was ethene. The structure of one molecule of ethene is shown in Figure 2. H
November 2021, Paper 1 Foundation, Q4(a)(iii) (2 marks): Calculate the relative formula mass of chromium oxide, Cr2O3. (relative atomic masses: O = 16, Cr = 52) (2) relative formula mass =
November 2021, Paper 1 Foundation, Q8(b) (2 marks): Dalton also investigated different gases. One of the gases that Dalton investigated was ethene. The structure of one molecule of ethene is shown in Figure 8. H
November 2021, Paper 2 Higher, Q4(b)(iv) (3 marks): Calculate the relative formula mass of a poly(chloroethene) molecule made from 2850 chloroethene molecules, C2H3Cl. (relative atomic masses: H = 1.00, C = 12.0,
November 2021, Paper 2 Higher, Q8(b) (2 marks): The compound phosphorus oxychloride has the formula POCl3. Calculate the percentage by mass of chlorine in phosphorus oxychloride. (relative atomic masses: O =
November 2021, Paper 2 Higher, Q8(c) (3 marks): When iron reacts with chlorine, iron chloride is formed. Two possible equations for this reaction are A Fe + Cl2 → FeCl2 B 2Fe + 3Cl2 → 2FeCl3 In an experiment,
November 2021, Paper 2 Foundation, Q4(d) (3 marks): Calculate the percentage by mass of copper in copper sulfate, CuSO4. (relative atomic masses: Cu = 63.5 relative formula mass of CuSO4 = 159.5) Give your answer
November 2021, Paper 2 Foundation, Q5(b) (3 marks): Tin reacts with chlorine to form tin chloride. A sample of tin chloride contains 1.19 g of tin and 1.42 g of chlorine. Calculate the empirical formula of this t
November 2020, Paper 1 Higher, Q3(a)(ii) (2 marks): Calculate the relative formula mass of copper carbonate, CuCO3 . (relative atomic masses: C = 12.0, O = 16.0, Cu = 63.5) (2) relative formula mass of CuCO3 =
November 2020, Paper 1 Higher, Q6(b)(ii) (3 marks): The equipment shown in Figure 7 can be used to find the mass of oxygen that combines with iron. lid crucible heat Figure 7 Describe how the equipment shown in F
November 2020, Paper 1 Higher, Q6(c) (4 marks): 2.24 g of iron combines with 0.96 g of oxygen to form an oxide of iron. Determine the formula of this oxide of iron and use it to complete the balanced equation
November 2020, Paper 1 Foundation, Q6(f) (3 marks): A titanium ore was analysed and found to contain 12 g of titanium atoms combined with 8.0 g of oxygen atoms. Calculate the empirical formula of this titanium co
November 2020, Paper 1 Foundation, Q9(a)(ii) (2 marks): Calculate the relative formula mass of copper carbonate, CuCO3 . (relative atomic masses: C = 12.0, O = 16.0, Cu = 63.5) (2) relative formula mass of CuCO3 =
November 2020, Paper 2 Foundation, Q7(c)(ii) (1 mark): Which calculation shows the percentage by mass of hydrogen in ethanoic acid? (relative atomic mass of hydrogen, H = 1, relative formula mass of ethanoic acid,
June 2019, Paper 1 Higher, Q2(d) (3 marks): In an experiment, 3.5 g of element A reacted with 4.0 g of element G to form a compound. Calculate the empirical formula of this compound. (relative atomic mass
June 2019, Paper 1 Higher, Q4(d)(i) (2 marks): Calculate the relative formula mass of calcium carbonate, CaCO3. (relative atomic masses: C = 12, O = 16, Ca = 40) (2) relative formula mass =
June 2019, Paper 1 Foundation, Q2(c)(ii) (2 marks): 63.0g of magnalium contains 3.15 g of magnesium. Calculate the percentage by mass of magnesium in the magnalium. (2) percentage of magnesium in the magnalium =.
June 2019, Paper 1 Foundation, Q8(d) (3 marks): In an experiment, 3.5 g of element A reacted with 4.0g of element G to form a compound. Calculate the empirical formula of this compound. (relative atomic masse
June 2019, Paper 1 Foundation, Q10(d)(i) (2 marks): Calculate the relative formula mass of calcium carbonate, CaCO3. (relative atomic masses: C = 12, O = 16, Ca = 40) (2) relative formula mass =
June 2019, Paper 2 Higher, Q2(c)(ii) (3 marks): Butane has the formula C4H10. Calculate the mass of carbon in 100 g of butane. Give your answer to three significant figures. (relative atomic masses: H = 1.00,
June 2019, Paper 2 Higher, Q7(d) (3 marks): A different hydrocarbon has a relative formula mass of 84. It has an empirical formula of CH2. Deduce the molecular formula of this hydrocarbon. You must show y
June 2019, Paper 2 Foundation, Q8(c)(ii) (3 marks): Butane has the formula C4H10. Calculate the mass of carbon in 100 g of butane. Give your answer to three significant figures. (relative atomic masses: H = 1.00,
June 2018, Paper 1 Foundation, Q4(a) (1 mark): The molecular formula of butene is C4H8. Which of the following is the empirical formula of butene? (1) A CH B CH2 C C4H8 D (CH2)4
June 2018, Paper 1 Foundation, Q4(b) (2 marks): Calculate the relative formula mass of butene, C4H8. (relative atomic masses: H = 1, C = 12) (2) relative formula mass
June 2018, Paper 2 Higher, Q3(a) (3 marks): Sodium metal tarnishes in air to form a layer of sodium oxide on its surface. 0.92 g of sodium combined with 0.32 g of oxygen in this oxide. Calculate the empir
June 2018, Paper 2 Foundation, Q9(a) (3 marks): Sodium metal tarnishes in air to form a layer of sodium oxide on its surface. 0.92 g of sodium combined with 0.32 g of oxygen in this oxide. Calculate the empir
Specimen, Paper 1 Higher, Q2(b) (2 marks): Calcium nitrate contains calcium ions and nitrate ions. Calculate the relative formula mass of calcium nitrate, Ca(NO3)2. (relative atomic masses: Ca = 40, N =
Specimen, Paper 1 Foundation, Q2(d) (1 mark): The formula of ammonium sulfate is (NH4)2SO4. What is the empirical formula of ammonium sulfate? (1) A NHSO B NH2SO2 C NH4SO4 D N2H8SO4
Specimen, Paper 1 Foundation, Q6(a)(i) (3 marks): Draw a graph of the mass of oxygen in magnesium oxide against the mass of magnesium used. (3) mass of oxygen in magnesium oxide / g mass of magnesium used / g
Specimen, Paper 1 Foundation, Q6(a)(ii) (1 mark): The result for experiment 5 is anomalous. The masses were all measured accurately. Suggest a reason for this anomalous result. (1)
Specimen, Paper 1 Foundation, Q6(c) (2 marks): Calcium nitrate contains calcium ions and nitrate ions. Calculate the relative formula mass of calcium nitrate, Ca(NO3)2. (relative atomic masses: Ca = 40, N =
Specimen, Paper 1 Foundation, Q6(d) (3 marks): Two oxides of lead, R and S, were analysed. The empirical formula of oxide R was found to be PbO. The results of the analysis of oxide S showed it contained 0.2
Specimen, Paper 2 Higher, Q2(d) (3 marks): A sample of calcium bromide contains 0.2 g calcium and 0.8 g bromine by mass. Calculate the empirical formula of calcium bromide. (relative atomic masses: Ca =
Specimen, Paper 2 Higher, Q4(a) (1 mark): Which of the following is the empirical formula for butane? (1) A CH B CH2 C C2H5 D C4H10
Specimen, Paper 2 Foundation, Q6(b) (2 marks): Calculate the relative formula mass of ethanol, C2H5OH. (relative atomic masses: H = 1, C = 12, O = 16) (2) relative formula mass =
Specimen, Paper 2 Foundation, Q7(g) (3 marks): A sample of calcium bromide contains 0.2 g calcium and 0.8 g bromine by mass. Calculate the empirical formula of calcium bromide. (relative atomic masses: Ca =
Specimen, Paper 2 Foundation, Q9(a) (1 mark): Which of the following is the empirical formula for butane? (1) A CH B CH2 C C2H5 D C4H10

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