Chemical formulae, equations and calculations: Edexcel International GCSE Chemistry questions

Every Edexcel International GCSE Chemistry exam question on Chemical formulae, equations and calculations (specification points 1.25–1.36), 2019–2025, with its mark scheme and examiner’s report.

All 249 questions on Chemical formulae, equations and calculations, as a list

June 2025, Paper 1, Q4(b)(i) (2 marks): Calculate the relative formula mass (Mr) of Ca3(PO4)2 (2) Mr of Ca3(PO4)2 =
June 2025, Paper 1, Q4(b)(ii) (2 marks): Calculate the percentage by mass of calcium in calcium phosphate. (2) percentage = %
June 2025, Paper 1, Q4(c) (1 mark): Calcium hydroxide can react with phosphoric acid to form calcium phosphate. Complete the equation for this reaction. (1) Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O
June 2025, Paper 1, Q6(e)(ii) (3 marks): Calculate the minimum mass of iron(III) oxide needed to produce a theoretical yield of 28 g of iron. [for Fe2O3 Mr = 160] (3) minimum mass of iron(III) oxide =
June 2025, Paper 1, Q6(e)(iii) (2 marks): The actual yield of iron from this sample is 21 g. Calculate the percentage yield of iron. (2) percentage yield = %
June 2025, Paper 1, Q7(a) (2 marks): Complete the chemical equation for this neutralisation reaction. Include the state symbols. (2) 2NaOH(aq) + H2SO4(aq) → +
June 2025, Paper 1, Q9(b) (3 marks): An organic compound contains this percentage composition by mass. C = 22.0% H = 4.6% Br = 73.4% Calculate the empirical formula of this compound. (3) empirical
June 2025, Paper 2, Q6(c) (4 marks): An excess of hydrogen reacts with 50.8 g of iodine. At equilibrium, the yield of hydrogen iodide is 80%. Calculate the volume, in cm3, of hydrogen iodide produc
June 2025 (R), Paper 1, Q7(a) (3 marks): Calculate the mass reading on the balance when all of the calcium carbonate has reacted. Assume that all of the carbon dioxide gas is lost through the cotton wo
June 2025 (R), Paper 1, Q11(b)(i) (1 mark): State how the results show that all the water has been removed from the crystals. (1)
June 2025 (R), Paper 1, Q11(b)(ii) (1 mark): Calculate the mass of anhydrous sodium sulfate remaining after heating. (1) mass of anhydrous sodium sulfate = g
June 2025 (R), Paper 1, Q11(b)(iii) (1 mark): Calculate the mass of water lost from the sodium sulfate crystals during heating. (1) mass of water = g
June 2025 (R), Paper 1, Q11(b)(iv) (3 marks): Use the student’s results to calculate x in the formula Na2SO4.xH2O [for Na2SO4 , Mr = 142 for H2O, Mr = 18] (3) x = J
June 2025 (R), Paper 2, Q3(c)(ii) (1 mark): Calculate the Mr of K2MnO4 (1) Mr =
June 2025 (R), Paper 2, Q4(a)(iii) (3 marks): The reaction produces 375 cm3 of hydrogen gas at room temperature and pressure (rtp). Show, by calculation, that the mass of lithium added is between 0.20 g and
June 2025 (R), Paper 2, Q6(c)(i) (1 mark): Complete the equation for the reaction. (1) 2K3PO4(aq) + CaCl2(aq) → Ca3(PO4)2(s) + KCl(aq)
June 2025 (R), Paper 2, Q6(c)(ii) (3 marks): The student reacts a solution containing 0.0400 mol of potassium phosphate with an excess of calcium chloride solution. The student obtains 5.70 g of calcium ph
November 2024, Paper 1, Q7(a)(ii) (1 mark): State how the student knows when all the water of crystallisation has been given off. (1)
November 2024, Paper 1, Q7(c) (4 marks): The decomposition of hydrated magnesium sulfate is shown in the equation. MgSO4.xH2O → MgSO4 + xH2O At the end of the reaction, the mass of MgSO4 remaining in t
November 2024, Paper 1, Q9(d)(ii) (3 marks): Calculate the total amount, in moles, of gas produced by the incomplete combustion of 3.7 g of butanol. (3) amount of gas = mol
November 2024, Paper 1, Q11(a)(i) (2 marks): Write a chemical equation for the reaction in stage 1. (2)
November 2024, Paper 1, Q11(a)(iii) (3 marks): This is the equation for stage 2. 2PbO + C → 2Pb + CO2 A mass of 892 tonnes of lead(II) oxide is heated in a furnace with an excess of carbon. Calculate the max
November 2024, Paper 1, Q11(b) (4 marks): A different oxide of lead contains 90.7% by mass of lead and 9.3% by mass of oxygen. Determine the empirical formula of this oxide of lead. (4) empirical formul
November 2024, Paper 2, Q4(b) (3 marks): This is the equation for the reaction between lithium and water. 2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g) The teacher collects 550 cm3 of hydrogen at rtp. Calculate
June 2024, Paper 1, Q3(b) (2 marks): One mole of Z contains 6.0 × 1023 atoms. Calculate the number of electrons in one mole of atoms of element Z. Give your answer in standard form. (2) number of e
June 2024, Paper 1, Q4(a)(ii) (2 marks): Calculate the relative formula mass (Mr) of caffeine. (2) Mr =
June 2024, Paper 1, Q4(a)(iii) (1 mark): Give the empirical formula for caffeine. (1)
June 2024, Paper 1, Q6(c)(ii) (4 marks): Potassium aluminium sulfate is normally found as a hydrated salt, with the formula KAl(SO4)2.xH2O When 23.7 g of the hydrated salt is heated to remove all the w
June 2024, Paper 1, Q7(c)(i) (2 marks): Give a chemical equation for this reaction. (2)
June 2024, Paper 1, Q8(d) (3 marks): Complete combustion of one mole of an alkane produces 396 g of carbon dioxide and 180 g of water. This is the equation for the reaction. alkane + xO2 → yCO2 + z
June 2024, Paper 2, Q6(b)(i) (1 mark): Show that the amount of sodium bromide used is 0.050 mol. (1)
June 2024, Paper 2, Q6(b)(ii) (2 marks): Show that the maximum theoretical mass of lead(II) bromide is approximately 9 g. [for PbBr2 Mr = 367] (2)
June 2024 (R), Paper 1, Q11(d) (3 marks): Another form of carbon has molecules with the formula Cx x represents the number of carbon atoms in each molecule. Each molecule of Cx has a mass of 1.40 × 10−2
June 2024 (R), Paper 1, Q12(a) (1 mark): Complete the equation for the reaction. (1) TaCl5(s) + H2(g) → Ta(s) + HCl(g)
June 2024 (R), Paper 1, Q12(b)(i) (1 mark): State how the data in the table shows that the reaction is complete. (1)
June 2024 (R), Paper 1, Q12(b)(ii) (3 marks): Use the data to show that the formula of tantalum chloride is TaCl5 [for tantalum, Ar = 181 for chlorine, Ar = 35.5] (3) QUESTION 12 CONTINUES ON NEXT PAGE.
June 2024 (R), Paper 1, Q12(c)(ii) (2 marks): 2000 mol of tantalum(V) oxide is heated with 500 000 g of carbon. Show by calculation that the carbon is in excess. [for carbon, Ar = 12] (2)
June 2024 (R), Paper 1, Q12(c)(iii) (2 marks): Calculate the maximum mass, in grams, of tantalum that can be obtained from 2000 mol of tantalum(V) oxide. [for tantalum, Ar = 181] (2) mass = g
June 2024 (R), Paper 2, Q1(b)(ii) (1 mark): Calculate the relative formula mass (Mr) of zinc sulfide. [for Zn, Ar = 65 for S, Ar = 32] (1) Mr =
June 2024 (R), Paper 2, Q3(b)(i) (2 marks): Complete the chemical equation for the reaction by balancing the equation and adding the state symbols. (2) Mg(s) + O2( ) → MgO( )
June 2024 (R), Paper 2, Q3(c)(iii) (3 marks): Calculate the minimum mass of magnesium needed to react with 25.0 cm3 of 2.00 mol / dm3 hydrochloric acid. [for Mg, Ar = 24] (3) mass = g
June 2024 (R), Paper 2, Q4(c)(ii) (3 marks): A mixture containing 500 mol of glucose is fermented. A mass of 5750 g of ethanol is obtained. Calculate the percentage yield. [for ethanol, Mr = 46] (3) percen
June 2024 (R), Paper 2, Q5(c) (4 marks): Crystals of hydrated sodium sulfate decompose when heated. This is the equation for the decomposition. Na2SO4.xH2O → Na2SO4 + xH2O A student uses this apparatus
June 2024 (R), Paper 2, Q6(a)(v) (3 marks): The oxygen gas in the tube has a volume of 17.8 cm3 at rtp. Calculate the mass, in grams, of oxygen gas in the tube. Give your answer to 3 significant figures.
November 2023, Paper 1, Q4(a)(vi) (1 mark): Calculate the Mr for carbon dioxide. (1) Mr =
November 2023, Paper 1, Q5(f) (3 marks): An organic compound has this percentage composition by mass. C = 19.2 % H = 4.0 % O = 12.8 % Br = 64.0 % Calculate the empirical formula of this compound. (3) e
November 2023, Paper 1, Q7(b) (3 marks): When chlorine gas is passed over heated iron powder, iron(III) chloride forms. This is the equation for the reaction. 2Fe + 3Cl2 → 2FeCl3 0.060 mol of chlorine
November 2023, Paper 1, Q8(d) (2 marks): C60 fullerene is a molecule made of 60 carbon atoms. The diagram shows the structure of C60 fullerene. One mole of atoms contains 6.0 × 1023 atoms. Determine th
November 2023, Paper 1, Q9(b)(i) (2 marks): Calculate the amount, in moles, of oxygen atoms in the sample of the metal oxide. (2) amount of oxygen atoms = mol
November 2023, Paper 1, Q9(b)(ii) (1 mark): The formula of the metal oxide is MO, where M represents the symbol of the metal. Deduce the amount, in moles, of M in the sample of the metal oxide. (1) amount
November 2023, Paper 1, Q9(b)(iii) (2 marks): Calculate the relative atomic mass of M. (2) relative atomic mass of M =
November 2023, Paper 1, Q9(b)(iv) (1 mark): Use the Periodic Table to identify metal M. (1)
November 2023, Paper 1, Q10(c)(i) (2 marks): In another experiment, 9.75 g of zinc is completely reacted with nitric acid. Show that the maximum possible mass of hydrated zinc nitrate crystals that could b
November 2023, Paper 1, Q10(c)(ii) (2 marks): The actual yield of hydrated zinc nitrate crystals is 36.4 g. Calculate the percentage yield of hydrated zinc nitrate crystals. (2) percentage yield = %
November 2023, Paper 2, Q6(c)(ii) (2 marks): Calculate the volume, in cm3, of carbon dioxide gas at rtp that would be produced from the 25.0 cm3 of the sodium carbonate solution. [at rtp, molar volume = 24
June 2023, Paper 1, Q6(a)(iii) (2 marks): Calculate the relative formula mass (Mr) of lead(II) nitrate, Pb(NO3)2 (2) Mr =
June 2023, Paper 1, Q7(c) (3 marks): Aluminium reacts with chlorine to form aluminium chloride. This is the equation for the reaction. 2Al + 3Cl2 → 2AlCl3 Calculate the minimum mass of chlorine nee
June 2023, Paper 1, Q8(d) (2 marks): The formula of pentanol is C5H11OH Write a chemical equation for the complete combustion of pentanol. (2)
June 2023, Paper 1, Q9(b)(i) (2 marks): Describe what the student should do next to make sure that all the water is removed from the hydrated sodium sulfate. (2)
June 2023, Paper 1, Q9(c) (5 marks): The table gives the student’s results. Mass of empty tube in g 15.83 Mass of tube and Na2SO4.xH2O in g 23.88 Mass of tube and Na2SO4 in g 19.38 Use the student’
June 2023, Paper 1, Q10(a)(i) (2 marks): Show by calculation that the zinc is in excess. (2)
June 2023, Paper 2, Q2(b)(i) (1 mark): What is the name of this type of reaction? (1) A addition B decomposition C oxidation D substitution
June 2023, Paper 2, Q2(b)(iii) (1 mark): Give the chemical equation for this reaction. (1)
June 2023, Paper 2, Q3(d)(i) (3 marks): Show by calculation that the empirical formula of propanol is C3H8O. (3)
June 2023, Paper 2, Q7(d) (4 marks): Calculate the volume, in dm3, of methane gas at rtp needed to produce 6.6 tonnes of hydrogen gas. [at rtp, molar volume = 24 dm3 1 tonne = 106 g] Give your answ
June 2023 (R), Paper 1, Q7(b)(i) (3 marks): Determine the molecular formula of this alkene. [for H2O, Mr = 18] (3) molecular formula =
June 2023 (R), Paper 1, Q7(c) (3 marks): The teacher burns 30.0 g of heptane. This is the equation for the complete combustion of heptane. C7H16 + 11O2 → 7CO2 + 8H2O Calculate the minimum mass of oxyge
June 2023 (R), Paper 1, Q9(a)(iii) (1 mark): Calcium nitrate decomposes when heated. Complete the chemical equation for the decomposition of calcium nitrate. (1) Ca(NO3)2 → CaO + NO2 + O2
June 2023 (R), Paper 1, Q10(d)(i) (3 marks): Compound X contains these percentages by mass. • carbon 60% • hydrogen 13.3% • oxygen 26.7% Compound X has an Mr of 60 Determine the molecular formula of compou
June 2023 (R), Paper 2, Q5(b) (2 marks): A solution containing 0.150 mol of lead(II) nitrate is reacted with an excess of potassium bromide solution. A mass of 49.6 g of pure, dry lead(II) bromide is p
June 2023 (R), Paper 2, Q6(d) (4 marks): This is the equation for the reaction between sodium and water. 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) A mass of 0.750 g of sodium is reacted with an excess of wa
January 2023, Paper 1, Q6(e) (2 marks): A different polymer molecule contains 10 600 atoms of carbon, 10 600 atoms of hydrogen and 31 800 atoms of chlorine. Determine the empirical formula of this pol
January 2023, Paper 1, Q8(a)(iii) (1 mark): Calculate the relative formula mass (Mr) of Na3N [for Na, Ar = 23 for N, Ar = 14] (1) Mr =
January 2023, Paper 1, Q11(a)(ii) (3 marks): The student adds 0.75 g of magnesium to 0.025 mol of nitric acid. Calculate the mass of magnesium, in grams, that remains at the end of the reaction. [for magne
January 2023, Paper 1, Q12(a)(i) (1 mark): Give a reason why the student repeats steps 3 and 4 until the mass is constant. (1)
January 2023, Paper 1, Q12(a)(ii) (1 mark): Calculate the mass of BaCl2 that forms in tube A. (1)
January 2023, Paper 1, Q12(a)(iii) (1 mark): Calculate the mass of water lost. (1)
January 2023, Paper 1, Q12(a)(iv) (3 marks): Determine the value of x in BaCl2 . xH2O Show your working. [for BaCl2 , Mr = 208 for H2O, Mr = 18] (3) x =
January 2023, Paper 1, Q12(c)(iii) (2 marks): Calculate the maximum number of water molecules in tube B after the sample of hydrated copper(II) sulfate has completely reacted. One mole of any substance cont
January 2023, Paper 2, Q2(b)(i) (1 mark): Give the number of different elements in C10H16N2O3S (1)
January 2023, Paper 2, Q2(b)(ii) (1 mark): Determine the number of atoms in a molecule of C10H16N2O3S (1)
January 2023, Paper 2, Q5(c) (3 marks): Copper can be produced by reacting an oxide of copper with methane. The diagram shows the apparatus used. excess methane burning methane gas oxide of copper in
January 2023, Paper 2, Q7(c) (4 marks): A sample of hydrazine is completely decomposed. This is the equation for the decomposition of hydrazine. 3N2H4(g) → 4NH3(g) + N2(g) The products of the decompos
January 2023 (R), Paper 1, Q5(a)(ii) (1 mark): Determine the relative molecular mass (Mr) of methanoic acid. (1) Mr =
January 2023 (R), Paper 1, Q5(c) (3 marks): Calculate the empirical formula of the organic compound with this composition by mass. C = 52.2% H = 13.0% O = 34.8% (3) empirical formula =
January 2023 (R), Paper 1, Q7(c)(i) (2 marks): Explain why the student lifts the lid. (2)
January 2023 (R), Paper 1, Q7(c)(ii) (2 marks): The mass of magnesium oxide formed is less than expected. Describe what the student should do next to obtain a more accurate value for the mass of magnesium oxi
January 2023 (R), Paper 1, Q8(a)(ii) (2 marks): Calculate the maximum mass of lead(II) oxide that can be formed from 5.34 g of lead(II) carbonate. [for PbCO3, Mr = 267 for PbO, Mr = 223] (2) maximum mass = g
January 2023 (R), Paper 1, Q9(a)(i) (1 mark): Complete the equation for the reaction by adding the state symbols. (1) Zn ( ) + 2HNO3 ( ) → Zn(NO3)2 ( ) + H2 ( )
January 2023 (R), Paper 1, Q9(c) (2 marks): The formula for the zinc nitrate crystals is Zn(NO3)2.6H2O When zinc nitrate crystals are heated, the products are zinc oxide, nitrogen dioxide (NO2), oxygen an
January 2023 (R), Paper 2, Q1(d) (1 mark): Give the number of different elements present in glucose, C6H12O6 (1)
January 2023 (R), Paper 2, Q3(b)(i) (2 marks): Calculate the percentage of sulfur in the fuel. (2) percentage of sulfur = %
January 2023 (R), Paper 2, Q3(b)(ii) (3 marks): When the fuel burns, the 600 g of sulfur produces sulfur dioxide gas. S + O2 → SO2 Calculate the volume, in cm3, of sulfur dioxide gas that would be produced at
January 2023 (R), Paper 2, Q5(c)(i) (1 mark): Complete the equation for the reaction. (1) Ca3(PO4)2 + C → Ca3P2 + CO
January 2023 (R), Paper 2, Q5(d) (2 marks): Calcium phosphide reacts with water to form calcium hydroxide and phosphine, PH3 Give a chemical equation for this reaction. (2)
June 2022, Paper 1, Q5(a)(ii) (1 mark): Calculate the relative formula mass (Mr) of C5H12 (1) Mr of C5H12 =
June 2022, Paper 1, Q6(a)(iii) (2 marks): The student uses 0.090 g of magnesium and 0.025 mol of hydrochloric acid. Show by calculation that the hydrochloric acid is in excess. (2)
June 2022, Paper 1, Q7(c)(i) (1 mark): Calculate the mass of CuSO4 formed. (1) mass of CuSO4 = g
June 2022, Paper 1, Q7(c)(ii) (1 mark): Calculate the mass of water formed. (1) mass of water = g
June 2022, Paper 1, Q7(c)(iii) (3 marks): Show that the value of x is approximately 4 [Mr of CuSO4 = 159.5 Mr of H2O = 18] (3)
June 2022, Paper 1, Q7(c)(iv) (1 mark): The actual value of x is 5 Give a reason why the calculated value of x is lower than the actual value. (1)
June 2022, Paper 1, Q9(b)(i) (2 marks): Describe what the scientist should do next to make sure that all the red lead oxide has reacted. (2)
June 2022, Paper 1, Q9(b)(ii) (3 marks): The red lead oxide used in the reaction has a mass of 5.48 g. Calculate the maximum mass of yellow lead oxide that could form. [Mr of Pb3O4 = 685 Mr of PbO = 22
June 2022, Paper 1, Q10(b)(ii) (1 mark): When ammonia reacts with sulfuric acid, ammonium sulfate is formed. Write a chemical equation for this reaction. (1)
June 2022, Paper 1, Q10(c)(i) (2 marks): Calculate the percentage of nitrogen in ammonium nitrate. [Mr of NH4NO3 = 80] (2) percentage of nitrogen = %
June 2022, Paper 1, Q10(c)(ii) (4 marks): Fertilisers add nitrogen to the soil to help plants grow. Ammonia and ammonium sulfate can both be used as fertilisers. Discuss the advantages and disadvantages
June 2022, Paper 2, Q5(a)(i) (2 marks): Show that the empirical formula of the compound is CH2O (2)
June 2022, Paper 2, Q6(a) (4 marks): This is the equation for the reaction in stage 1. TiO2 + 2Cl2 + C → TiCl4 + CO2 Calculate the volume, in dm3, of chlorine gas at rtp needed to react completely
June 2022 (R), Paper 1, Q2(a) (2 marks): Complete the table by giving the name of each piece of apparatus and a unit used for the quantity it measures. (2) Apparatus Name Unit 0 20 40 60 80 100
June 2022 (R), Paper 1, Q4(d)(iii) (3 marks): The reaction with sodium produces 0.036 g of hydrogen gas. One mole of hydrogen gas contains 6.0 × 1023 molecules. Calculate the number of molecules of hydrogen
June 2022 (R), Paper 1, Q5(b)(ii) (1 mark): Calculate the amount, in mol, of carbon dioxide produced. [for carbon dioxide Mr = 44] (1) amount of carbon dioxide = mol
June 2022 (R), Paper 1, Q5(b)(iii) (1 mark): Use the equation to determine the amount, in mol, of XCO3 that decomposed. (1) amount of XCO3 = mol
June 2022 (R), Paper 1, Q5(b)(iv) (2 marks): Use the mass of XCO3 and your answer to (b)(iii) to calculate the relative formula mass (Mr) of XCO3 (2) Mr of XCO3 =
June 2022 (R), Paper 1, Q5(b)(v) (2 marks): Use your answer to (b)(iv) and the Periodic Table on page 2 to determine the identity of the Group 2 metal X. Show your working. (2) identity of X =
June 2022 (R), Paper 1, Q6(d) (1 mark): Silicon hydride reacts with oxygen to form silicon dioxide and water. Write a chemical equation for the reaction between silicon hydride and oxygen. (1)
June 2022 (R), Paper 1, Q11(a)(iii) (3 marks): The table shows the teacher’s results. Mass in g empty weighing boat 14.72 weighing boat and tungsten oxide 17.04 weighing boat and tungsten 16.56 Use the teach
June 2022 (R), Paper 1, Q11(a)(iv) (1 mark): The teacher wears eye protection and a lab coat during the experiment. Give one other safety precaution the teacher should take. (1)
June 2022 (R), Paper 1, Q11(b) (3 marks): In industry, tungsten oxide is reduced on a large scale using hydrogen. The percentage yield of tungsten is 73.5% This is the equation for the reaction. WO3 + 3
June 2022 (R), Paper 2, Q2(b)(i) (1 mark): How many different types of atom are in KMnO4? (1) A 3 B 4 C 6 D 7
June 2022 (R), Paper 2, Q2(b)(ii) (1 mark): Calculate the relative formula mass (Mr) of KMnO4 (1) Mr =
June 2022 (R), Paper 2, Q3(c)(i) (2 marks): The complete combustion of one mole of the alkane produces 220 g of carbon dioxide and 108 g of water. Calculate the values of y and z. [Mr of CO2 = 44 Mr of H2
June 2022 (R), Paper 2, Q5(c)(iii) (3 marks): Aspirin has this percentage composition by mass. C = 60.00 % H = 4.44 % O = 35.56 % Show by calculation that the empirical formula of aspirin is C9H8O4 (3)
June 2022 (R), Paper 2, Q7(d)(i) (3 marks): Show by calculation that the nitrogen is in excess. (3)
June 2022 (R), Paper 2, Q7(d)(ii) (3 marks): The yield of ammonia at equilibrium is 20 %. Calculate the volume, in dm3, of ammonia formed from 120 dm3 of hydrogen. (3) volume of ammonia = dm3
January 2022, Paper 1, Q5(b)(iv) (2 marks): One mole of magnesium has a mass of 24.32 g. There are 6.022 × 1023 atoms in one mole. Calculate the mass, in grams, of one atom of magnesium. Give your answer
January 2022, Paper 1, Q5(c) (1 mark): The equation for the reaction between magnesium and oxygen is 2Mg + O2 → 2MgO Determine the maximum amount, in moles, of magnesium oxide that can be produced fr
January 2022, Paper 1, Q6(b) (1 mark): Calculate the relative formula mass (Mr) of sodium oxide, Na2O, using information from the Periodic Table. (1) Mr =
January 2022, Paper 1, Q6(e) (1 mark): When sodium oxide is heated it reacts to form sodium metal and sodium peroxide, Na2O2 Complete the equation for this reaction. (1) Na2O →
January 2022, Paper 1, Q8(c)(i) (3 marks): Another compound, G, has this percentage composition by mass. C = 37.8 % H = 6.3 % Cl = 55.9 % Show by calculation that the empirical formula of compound G is C
January 2022, Paper 1, Q8(c)(ii) (2 marks): The relative formula mass (Mr) of G is 127 Determine the molecular formula of G. (2) molecular formula =
January 2022, Paper 1, Q9(b) (2 marks): Complete the equation for the reaction by adding the state symbols. (2) CaCO3( ) + 2HCl( ) → CaCl2(aq) + H2O( ) + CO2( )
January 2022, Paper 1, Q9(c)(i) (1 mark): Give a reason why there are some calcium carbonate chips remaining in the flask when the reaction stops. (1)
January 2022, Paper 1, Q9(c)(iii) (2 marks): Use the graph to determine the amount, in moles, of carbon dioxide produced during the reaction. [Mr of CO2 = 44] (2) amount = mol
January 2022, Paper 1, Q11(b) (5 marks): The equation for the decomposition of hydrated zinc sulfate is ZnSO4·7H2O(s) → ZnSO4(s) + 7H2O(l) The student records these masses. mass of boiling tube = 41.64
January 2022, Paper 1, Q11(c)(i) (1 mark): Calculate the volume, in cm3, of pure water collected. (1) volume of pure water = cm3
January 2022, Paper 1, Q11(c)(ii) (2 marks): Explain an improvement to the apparatus that would increase the percentage yield of pure water. (2)
January 2022, Paper 2, Q4(c) (4 marks): The teacher adds 0.150 g of lithium to an excess of water and collects the hydrogen gas produced. The equation for the reaction is 2Li(s) + 2H2O(l) → 2LiOH(aq)
January 2022 (R), Paper 1, Q5(d)(iv) (2 marks): Magnesium sulfide reacts with hydrochloric acid to form magnesium chloride and hydrogen sulfide gas, H2S Give the chemical equation for this reaction. (2)
January 2022 (R), Paper 1, Q6(a) (1 mark): Calculate the relative formula mass (Mr) of ocimene. (1) Mr =
January 2022 (R), Paper 1, Q6(b) (2 marks): Using ocimene as an example, explain what is meant by the term empirical formula. (2)
January 2022 (R), Paper 1, Q7(b) (4 marks): The equation for the thermal decomposition of potassium hydrogencarbonate is 2KHCO3 → K2CO3 + H2O + CO2 Calculate the maximum mass of K2CO3 that could be produc
January 2022 (R), Paper 1, Q8(a) (1 mark): Complete the equation for the reaction by adding the state symbols. (1) Zn ( ) + H2SO4 ( ) → ZnSO4 ( ) + H2 ( )
January 2022 (R), Paper 1, Q8(c)(ii) (1 mark): At the end of the experiment there is no zinc left in the flask. Give a conclusion the student could make from this observation. (1)
January 2022 (R), Paper 1, Q10(a) (1 mark): A student is given a pure sample of sodium carbonate crystals and is told that the formula of the crystals is Na2CO3.xH2O State what xH2O in the formula shows a
January 2022 (R), Paper 1, Q10(b)(i) (1 mark): Calculate the mass of sodium carbonate left after heating and cooling. (1) mass of sodium carbonate = g
January 2022 (R), Paper 1, Q10(b)(ii) (1 mark): Calculate the mass of H2O lost from the sodium carbonate crystals during heating. (1) mass of H2O = g
January 2022 (R), Paper 1, Q10(b)(iii) (3 marks): Show that the student’s results suggest that the formula of the sodium carbonate crystals is Na2CO3.7H2O [Mr of Na2CO3 = 106 Mr of H2O = 18] (3)
January 2022 (R), Paper 1, Q10(c)(i) (2 marks): The student did not make any mistakes in their measurements. Explain what could have caused the student’s value for x to be too low. (2)
January 2022 (R), Paper 1, Q10(c)(ii) (2 marks): Describe how the student could improve the method to obtain a more accurate value for x. (2)
January 2022 (R), Paper 1, Q11(b) (2 marks): The equation for the reaction is Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s) 50 cm3 of copper(II) sulfate solution contains 0.025 mol CuSO4 A mass of 3 g of zinc
January 2022 (R), Paper 2, Q2(c)(ii) (1 mark): Calculate the relative molecular mass (Mr) of this alkane. (1) Mr =
January 2022 (R), Paper 2, Q5(a)(ii) (3 marks): A mass of 6.4 tonnes of sulfur is burned to produce sulfur dioxide gas. Calculate the maximum volume, in dm3, of sulfur dioxide gas that can be produced at rtp.
January 2022 (R), Paper 2, Q5(c) (2 marks): In stage 3, the sulfur trioxide is reacted with concentrated sulfuric acid to form a liquid called oleum, H2S2O7 The oleum is then added to water to form concen
January 2022 (R), Paper 2, Q5(d) (2 marks): Sulfuric acid reacts with ammonia to form ammonium sulfate, (NH4)2SO4 Calculate the percentage by mass of nitrogen in ammonium sulfate. [Mr of (NH4)2SO4 = 132]
November 2021, Paper 1, Q6(b)(i) (2 marks): Show by calculation that the empirical formula of compound Z is CH3O (2)
November 2021, Paper 1, Q6(b)(ii) (2 marks): The relative formula mass (Mr) of compound Z is 62 Deduce the molecular formula of compound Z. (2) molecular formula =
November 2021, Paper 1, Q7(a)(i) (1 mark): Give a chemical equation for this reaction. (1)
November 2021, Paper 1, Q9(b)(i) (1 mark): Give a reason for the cotton wool plug in the conical flask. (1)
November 2021, Paper 1, Q9(b)(ii) (3 marks): The student adds 2.12 g of sodium carbonate to an excess of dilute hydrochloric acid. The chemical equation for the reaction is Na2CO3(s) + 2HCl(aq) → 2NaCl(aq)
November 2021, Paper 1, Q9(b)(iii) (1 mark): Suggest why the mass of carbon dioxide produced is less than the calculated maximum mass. (1)
November 2021, Paper 1, Q10(b)(i) (2 marks): Calculate the amount, in moles, of ethanol in 15.5 cm3 of ethanol. (2) amount = mol
November 2021, Paper 1, Q10(b)(ii) (1 mark): Calculate the number of molecules of ethanol in 15.5 cm3 of ethanol. (1) number of molecules =
November 2021, Paper 1, Q11(d) (2 marks): 1.00 g of aluminium is added to 0.0600 mol of dilute sulfuric acid. The equation for the reaction is 2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2(g) Show by calcul
November 2021, Paper 2, Q3(a)(i) (2 marks): Complete the chemical equation for the reaction. (2) 2H2S( ) + SO2( ) → S(s) + H2O( )
November 2021, Paper 2, Q4(c)(ii) (1 mark): Give a chemical equation for the reaction between potassium oxide and water. (1)
November 2021, Paper 2, Q5(d) (3 marks): Aluminium is extracted from aluminium oxide. The overall equation for the process is 2Al2O3 → 4Al + 3O2 Calculate the maximum mass, in grams, of aluminium that
November 2021, Paper 2, Q6(c)(ii) (2 marks): A sample of vinegar containing 0.0030 mol of CH3COOH is poured into a flask. Calculate the maximum volume, in cm3, of carbon dioxide gas formed at rtp when exce
June 2021, Paper 1, Q10(b)(i) (1 mark): Calculate the mass of lead formed. (1) mass of lead = g
June 2021, Paper 1, Q10(b)(ii) (1 mark): Calculate the mass of oxygen removed from the lead oxide. (1) mass of oxygen = g
June 2021, Paper 1, Q10(b)(iii) (4 marks): Determine the empirical formula of the lead oxide. (4) empirical formula of the lead oxide
June 2021, Paper 1, Q10(c)(ii) (3 marks): Show that the maximum mass of lead(II) chloride that can be made from 0.0370 mol of hydrochloric acid is about 5 g. [Mr of PbCl2 = 278] (3) maximum mass = g
June 2021, Paper 2, Q6(c)(ii) (4 marks): Calculate the maximum volume, in dm3, of chlorine gas at rtp that can be obtained from 23.4 tonnes of molten sodium chloride. [1 tonne = 106 g] [Mr of NaCl = 58
January 2021, Paper 1, Q3(d) (1 mark): Complete the chemical equation for the reaction between lead nitrate and potassium iodide. (1) Pb(NO3)2(aq) + KI(aq) → PbI2(s) + KNO3(aq)
January 2021, Paper 1, Q10(c)(i) (2 marks): An alkane contains 82.8% carbon and 17.2% hydrogen by mass. Show by calculation that the empirical formula of this alkane is C2H5 (2)
January 2021, Paper 1, Q10(c)(ii) (1 mark): Deduce the molecular formula of this alkane. (1)
January 2021, Paper 1, Q10(d) (3 marks): The equation for the complete combustion of one mole of an alkane can be represented by alkane + ZO2 → XCO2 + YH2O Complete combustion of one mole of the alkane
January 2021, Paper 1, Q11(c) (2 marks): In another experiment, the student adds 0.55 g of zinc to a solution containing 2.50 × 10−2 moles of hydrochloric acid. Use the equation to show that hydrochlor
January 2021, Paper 2, Q6(c)(ii) (3 marks): Calculate the maximum mass, in grams, of silver chloride that could be produced. [Mr of AgCl = 143.5] (3) maximum mass = g
January 2021, Paper 2, Q6(c)(iii) (2 marks): In an experiment using different solutions, the mass of silver chloride produced is 0.744 g. The maximum mass of silver chloride that could be produced is 0.850
January 2021, Paper 2, Q7(c)(iii) (5 marks): Show that the car produces less than 100 g of carbon dioxide per km. [molar volume of carbon dioxide at rtp = 24 000 cm3] (5)
January 2021 (R), Paper 1, Q6(b)(i) (1 mark): Use the graph to find the minimum volume of acid needed to react with all of the zinc. (1)
January 2021 (R), Paper 1, Q6(b)(ii) (2 marks): The student repeats the investigation, using hydrochloric acid of double the original concentration. Determine the volume of hydrogen that would be collected us
January 2021 (R), Paper 1, Q8(c)(i) (5 marks): The fuel tank of a car contains 50.0 dm3 of octane. Calculate the mass, in kg, of carbon dioxide formed if all the octane in the fuel tank undergoes complete co
January 2021 (R), Paper 1, Q10(b)(ii) (3 marks): The student produces dry crystals of hydrated copper(II) sulfate from the saturated solution. He calculates that 6.40 g of dry crystals should be formed. The ma
January 2021 (R), Paper 1, Q10(c)(i) (3 marks): Gypsum is hydrated calcium sulfate. A sample of gypsum contains 79% of calcium sulfate by mass. Calculate the value of x in CaSO4.xH2O [Mr of CaSO4 = 136 Mr of
January 2021 (R), Paper 2, Q7(a) (2 marks): Calculate the amount, in moles, of hydrocarbon X in the sample. [molar volume of a gas = 24 000 cm3 at rtp] (2) amount of hydrocarbon X = mol
January 2021 (R), Paper 2, Q7(b) (2 marks): The mass of the sample of hydrocarbon X is 1.45 g. Show that the relative molecular mass (Mr) of X is 58 (2) Mr =
November 2020, Paper 1, Q4(c)(ii) (1 mark): Calculate the relative formula mass of ammonium sulfate, (NH4)2SO4 (1) relative formula mass =
November 2020, Paper 1, Q4(c)(iii) (3 marks): Calculate the mass, in grams, of nitrogen in 1.0 kg of ammonium sulfate. (3) mass = g
November 2020, Paper 1, Q9(b)(i) (1 mark): Give a reason why the crucible and contents are heated for a further three minutes. (1)
November 2020, Paper 1, Q9(b)(ii) (2 marks): The student considered using a lid on the crucible in the experiment. Suggest an advantage and a disadvantage of using a lid on the crucible. (2) advantage disa
November 2020, Paper 1, Q9(c)(i) (1 mark): Calculate the mass of sodium hydrogencarbonate that the student uses. (1) mass = g
November 2020, Paper 1, Q9(c)(ii) (3 marks): Using this equation, calculate the maximum mass of sodium carbonate (Na2CO3) that could form in the student’s reaction. 2NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g)
November 2020, Paper 1, Q9(d)(i) (2 marks): Calculate the percentage yield from the student’s experiment. (2) percentage yield = %
November 2020, Paper 1, Q9(d)(ii) (1 mark): Other than spillages, suggest a possible reason why the student’s actual yield is less than expected. (1)
November 2020, Paper 1, Q10(a) (2 marks): When a sample of red lead oxide is heated, it changes into a yellow solid and a gas forms that relights a glowing splint. Complete the word equation for this re
November 2020, Paper 1, Q10(b) (3 marks): A sample of one of the oxides of lead contains 86.6% lead and 13.4% oxygen by mass. Show by calculation that the sample is lead(IV) oxide, PbO2 [Ar of Pb = 207
November 2020, Paper 1, Q10(c)(i) (2 marks): Complete the chemical equation for the reaction. Pb3O4( ) + 4HNO3( ) → Pb(NO3)2(aq) + PbO2(s) + H2O(l) (2)
November 2020, Paper 2, Q7(a) (3 marks): Potassium carbonate reacts with dilute hydrochloric acid to produce carbon dioxide gas. The equation for the reaction is K2CO3(s) + 2HCl(aq) → 2KCl(aq) + H2O(l)
November 2020 (R), Paper 1, Q4(a) (1 mark): Complete the chemical equation for this reaction. (1) H2O2 → H2O + O2
November 2020 (R), Paper 1, Q5(c)(i) (3 marks): Calculate the empirical formula of this compound. (3) empirical formula =
November 2020 (R), Paper 1, Q5(c)(ii) (2 marks): The relative molecular mass (Mr) of the compound is 62 Determine the molecular formula of the compound. (2) molecular formula =
November 2020 (R), Paper 1, Q7(c)(i) (2 marks): Calculate the relative molecular mass (Mr) of zinc sulfate crystals. (2) Mr =
November 2020 (R), Paper 1, Q7(c)(ii) (2 marks): The student uses 0.0200 mol of dilute sulfuric acid in her preparation. Show that the maximum mass of zinc sulfate crystals that the student could obtain is abo
November 2020 (R), Paper 1, Q7(c)(iii) (3 marks): The student obtains a mass of 4.28 g of zinc sulfate crystals. Calculate the percentage yield of the zinc sulfate crystals. Give your answer to three significan
November 2020 (R), Paper 1, Q8(c) (4 marks): A student uses this apparatus to find the mass of magnesium oxide that forms when a known mass of magnesium is heated. crucible lid magnesium ribbon heat This i
November 2020 (R), Paper 2, Q7(d) (4 marks): Methanoic acid reacts with sodium carbonate to form sodium methanoate, carbon dioxide and water. The equation for the reaction is 2HCOOH + Na2CO3 → 2HCOONa + CO
January 2020, Paper 1, Q5(e)(i) (2 marks): Show that the empirical formula of the compound is CH2F (2)
January 2020, Paper 1, Q5(e)(ii) (2 marks): The relative molecular mass (Mr) of the compound is 66. Determine the molecular formula of the compound. (2) molecular formula =
January 2020, Paper 1, Q10(a)(i) (1 mark): Complete the chemical equation for the reaction in stage 1. (1) NH3 + O2  NO + H2O
January 2020, Paper 1, Q10(b) (1 mark): Give a chemical equation for the reaction of nitrogen monoxide and oxygen in stage 2. (1)
January 2020, Paper 1, Q10(c)(i) (4 marks): The equation for the reaction in stage 3 is 3NO2 + H2O → 2HNO3 + NO Calculate the maximum mass, in tonnes, of nitric acid that could be produced in this reactio
January 2020, Paper 1, Q10(c)(ii) (1 mark): Suggest what use can be made of the nitrogen monoxide gas formed in stage 3. (1) QUESTION 10 CONTINUES ON NEXT PAGE
January 2020, Paper 1, Q10(d) (3 marks): When copper(II) oxide reacts with dilute nitric acid, copper(II) nitrate is produced. The equation for the reaction is CuO + 2HNO3 → Cu(NO3)2 + H2O 0.200 mol of
January 2020, Paper 2, Q2(c)(ii) (1 mark): Calculate the relative molecular mass (Mr) of this alkane. (1) Mr =
January 2020, Paper 2, Q3(c) (4 marks): When hydrated copper(II) sulfate crystals are heated, anhydrous copper(II) sulfate forms. A mass of 12.5 g of hydrated copper(II) sulfate crystals is heated in
January 2020, Paper 2, Q7(c)(i) (1 mark): What is the name for this type of reaction? (1) A addition B combustion C decomposition D neutralisation
January 2020, Paper 2, Q7(c)(ii) (4 marks): Calculate the total volume, in dm3, of gas produced at rtp when 7.7 g of magnesium nitrate completely reacts. [Assume that the molar volume of a gas at rtp is 2
January 2020 (R), Paper 1, Q3(d)(ii) (2 marks): The product of the reaction between iron and chlorine is iron(III) chloride. The ions in iron(III) chloride are Fe3+ and Cl− Use this information to give the ch
January 2020 (R), Paper 1, Q11(a) (2 marks): Solid oxides of copper can be reduced by reacting them with methane gas. Complete the equation for the reaction between copper(II) oxide and methane. Include st
January 2020 (R), Paper 1, Q11(b)(i) (4 marks): The teacher heats the oxide of copper until the reaction is complete. The table shows the teacher’s results. Mass in g empty weighing boat 15.05 weighing boat +
January 2020 (R), Paper 1, Q11(b)(ii) (1 mark): The teacher wears safety glasses and a lab coat during the demonstration. Give one other safety precaution that she should take. (1)
January 2020 (R), Paper 1, Q11(c)(iii) (4 marks): Calculate the maximum mass, in tonnes, of iron that can be produced when 30.0 tonnes of iron(III) oxide are reacted with an excess of carbon. [1 tonne = 1.0 × 1
January 2020 (R), Paper 1, Q11(c)(iv) (2 marks): A mixture of 25 000 mol of iron(III) oxide and 840 000 g of carbon is heated. Use this equation to show that the iron(III) oxide is in excess. Fe2O3 + 3C o 2Fe
January 2020 (R), Paper 2, Q3(d) (2 marks): The chemical equation for the reaction between solutions of silver nitrate and potassium chloride is AgNO3(aq) + KCl(aq) o AgCl(s) + KNO3(aq) A student adds an
January 2020 (R), Paper 2, Q5(c)(i) (3 marks): A mass of 0.500 g of lithium reacts with an excess of water. Calculate the volume, in cm3, of hydrogen gas produced at rtp. [molar volume of a gas at rtp = 24 0
January 2020 (R), Paper 2, Q7(a)(iv) (2 marks): When 4 mol of glucose is fermented, a mass of 55.2 g of ethanol is produced. Show that the percentage yield of ethanol is 15%. [Mr of C2H5OH = 46] (2)
June 2019, Paper 1, Q1(c) (1 mark): The formula of potassium permanganate is KMnO4 How many different elements are there in potassium permanganate? (1) A 3 B 4 C 6 D 7
June 2019, Paper 1, Q8(a) (1 mark): The first stage is to convert ethene into 1,2-dichloroethane, C2H4Cl2 Ethene is reacted with hydrogen chloride and oxygen. Complete the chemical equation for th
June 2019, Paper 1, Q8(b) (1 mark): In the second stage, 1,2-dichloroethane is converted into chloroethene. C2H4Cl2 → C2H3Cl + HCl This is a thermal decomposition reaction. State what is meant by
June 2019, Paper 1, Q9(a) (2 marks): Show, by calculation, that the empirical formula of this compound is CBrF3 (2)
June 2019, Paper 1, Q11(a) (2 marks): Calculate the mass of oxygen required to react with 32 g of methane. [M, of methane = 16] (2) mass of oxygen =.... ....g
June 2019, Paper 1, Q14(f)(i) (3 marks): In an experiment, a student completely reacts 9.54 g copper(II) oxide. Show that the maximum possible mass of CuSO4.5H2O crystals that can be obtained is about
June 2019, Paper 1, Q14(f)(ii) (2 marks): In this experiment, the actual yield of CuSO4.5H2O crystals is 23.92 g. Calculate the percentage yield of CuSO4.5H2O (2) percentage yield = %
June 2019, Paper 1, Q15(b)(i) (1 mark): Calculate the mass of (NH4)2SO4.Fe2(SO4)3 produced by heating. (1) mass of (NH4)2SO4.Fe2(SO4)3 = g
June 2019, Paper 1, Q15(b)(ii) (1 mark): Calculate the mass of water produced. (1) mass of water = g
June 2019, Paper 1, Q15(b)(iii) (4 marks): Calculate the value of x. [Mr of (NH4)2SO4.Fe2(SO4)3 = 532 and Mr of H2O = 18] Give your answer to the nearest whole number. (4) value of x =
June 2019, Paper 2, Q8(b)(i) (2 marks): Calculate the amount, in moles, of chlorine gas produced. Assume one mole of chlorine gas occupies 24 000 cm3. (2) amount of chlorine = mol
June 2019, Paper 2, Q8(b)(ii) (1 mark): Determine the amount, in moles, of NaClO in 4.00 cm3 of bleach. (1) amount of NaClO = mol
June 2019, Paper 2, Q8(b)(iii) (2 marks): Calculate the concentration, in mol/dm3, of the bleach solution. (2) concentration = mol/dm3
June 2019 (R), Paper 1, Q2(c) (1 mark): Sodium burns in oxygen to produce sodium oxide. Complete the equation for this reaction. (1) Na + O2 → Na2O
June 2019 (R), Paper 1, Q5(b) (2 marks): This is the equation for the reaction between marble chips and dilute hydrochloric acid. Complete the equation by adding the state symbols. (2) CaCO3 ( ) + 2HCl
June 2019 (R), Paper 1, Q6(a) (3 marks): Chloroethene has the percentage composition by mass C = 38.4% H = 4.8% Cl = 56.8% Show, by calculation, that the empirical formula of chloroethene is C2H3Cl (3)
June 2019 (R), Paper 1, Q6(b)(v) (1 mark): In stage 2, dichloroethane decomposes into chloroethene and hydrogen chloride. Give a chemical equation for this reaction. (1)
June 2019 (R), Paper 1, Q7(b)(i) (1 mark): Show by calculation that the relative formula mass of Mg(NO3)2.6H2O is 256. (1)
June 2019 (R), Paper 1, Q7(b)(ii) (3 marks): Show that the maximum mass of Mg(NO3)2.6H2O that could be made from 0.050 mol of nitric acid is about 6 g. (3)
June 2019 (R), Paper 1, Q7(b)(iii) (2 marks): The actual mass of crystals that the student obtains is 4.8 g. Calculate the percentage yield of Mg(NO3)2.6H2O in this experiment. (2) percentage yield = %
June 2019 (R), Paper 1, Q10(b)(ii) (1 mark): The mass of anhydrous copper(II) sulfate (CuSO4) used to make 25.0 cm3 of solution is 2.00 g. Calculate the amount, in moles, of CuSO4 in 2.00 g. [Mr of CuSO4 =
June 2019 (R), Paper 2, Q7(c) (4 marks): Calculate the volume, in dm3, of hydrogen gas at rtp that is produced when 10 tonnes of methane gas completely react with steam. [molar volume of hydrogen at rt

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