Formulae, equations and the mole: Edexcel International A Level Chemistry questions

Every Edexcel International A Level Chemistry exam question on Formulae, equations and the mole (specification points 1.1–1.5), 2019–2025, with its mark scheme and examiner’s report.

All 99 questions on Formulae, equations and the mole, as a list

June 2025, AS Unit 1, Q3 (1 mark): Which amount does not have a mass of approximately 6 g? A 0.33 mol water (H2O; Mr = 18) B 0.25 mol magnesium (Mg; Ar = 24.3) C 0.033 mol glucose (C6H12O6 ; Mr =
June 2025, AS Unit 1, Q4 (1 mark): How many molecules of H2O are present in 1 drop (0.050 cm3) of water? [L = 6.02 × 1023, density of water = 1 g cm–3] A 2.17 × 1026 B 6.69 × 1023 C 1.67 × 1022 D
June 2025, AS Unit 1, Q16 (1 mark): How many hydrogen atoms are in 14 g of methane? [L = 6.02 × 1023] A 5.268 × 1023 B 6.880 × 1023 C 2.107 × 1024 D 2.752 × 1024
January 2025, AS Unit 1, Q1 (1 mark): What is the total number of atoms in 8.8 g of carbon dioxide? [Mr value: CO2 = 44 Avogadro constant, L = 6.02 × 1023 mol–1] A 1.2 × 1023 B 3.6 × 1023 C 1.2 × 10
January 2025, AS Unit 1, Q3 (1 mark): A water molecule, containing the isotopes of hydrogen and oxygen, hydrogen‑1 and oxygen‑16, has a mass of 2.9908 × 10–23 g. What is the mass of an atomic mass u
January 2025, AS Unit 1, Q18 (1 mark): Which of these formulae are correct for the compound 1,4‑diethylcyclohexene? C10H18 C5H9 (i) (ii) (iii) skeletal formula molecular formula empirical formula A n
January 2025, Unit 4, Q20(c)(i) (2 marks): Complete the equation for the reaction of one mole of sucrose with nitric acid. (2) HO O C12H22O11 36HNO3 + NO2 + H2O + O OH
January 2025, Unit 4, Q20(c)(ii) (1 mark): Give one observation that would be seen during this reaction. (1)
October 2024, AS Unit 1, Q1 (1 mark): What is the molecular formula of naphthalene? A C10H8 B C10H10 C C12H10 D C12H12
October 2024, AS Unit 1, Q2 (1 mark): Magnesium azide is an ionic compound containing the azide ion, N3 – . The empirical formula of magnesium azide is A Mg3N B MgN2 C MgN3 D MgN6
October 2024, AS Unit 1, Q3 (1 mark): How many oxygen atoms are there in 0.0100 mol of H2SO4? [Avogadro constant, L = 6.020 × 1023 mol–1] A 6.020 × 1021 B 1.204 × 1022 C 2.408 × 1022 D 4.214 × 1022
October 2024, AS Unit 1, Q5 (1 mark): Diphosphane, P2H4 , reacts spontaneously with oxygen. xP2H4 + yO2 → P4O10 + zH2O The equation for this reaction is balanced when A x = 1 y = 6 z = 2 B x = 2 y =
October 2024, AS Unit 2, Q8 (1 mark): A 20 g sample of iron(III) sulfate, Fe2(SO4)3 , was dissolved in water. How many sulfate ions are in the solution formed? [Assume Mr Fe2(SO4)3 = 400 Avogadro co
October 2024, Unit 5, Q15(b) (2 marks): Butylamine has a fishy, ammonia-like smell. The exposure limit or safety level in the atmosphere for butylamine is 15 mg m−3 . Calculate the maximum number of b
June 2024, AS Unit 1, Q1 (1 mark): How many atoms are there in 10 g of methane? [Ar values: H = 1.0 C = 12.0 L = 6.02 × 1023 mol–1] A 3.76 × 1023 B 9.63 × 1023 C 1.88 × 1024 D 4.82 × 1024
June 2024, AS Unit 1, Q12 (1 mark): Which pair of compounds will not react to form a precipitate? A AgNO3(aq) and CaCl2(aq) B Ca(OH)2(aq) and CO2(g) C Ba(OH)2(aq) and HCl(aq) D KI(aq) and Pb(NO3)2
June 2024, AS Unit 1, Q13 (1 mark): What is observed when iron(II) carbonate reacts with ethanoic acid? A colourless solution B colourless solution and effervescence C green solution and effervesc
June 2024, AS Unit 1, Q14 (1 mark): Which is the simplest ionic equation for an alkali reacting with an acid? A 2H+(aq) + 2OH–(aq) → 2H2O(l) B H+(aq) + OH–(aq) → H2O(aq) C H+(aq) + OH–(aq) → H2O(l
June 2024, AS Unit 1, Q15(a) (2 marks): Silver chloride decomposes in light. This reaction was used in the first photographic plates. Write an equation for this decomposition. Include state symbols. (
June 2024, AS Unit 1, Q16(a)(i) (2 marks): Define relative atomic mass. (2)
June 2024, AS Unit 1, Q18(a)(i) (1 mark): Give the name of the second type of reaction. (1)
June 2024, AS Unit 1, Q18(a)(ii) (1 mark): Suggest why neutralisation does not occur in an unopened container of baking powder. (1)
June 2024, AS Unit 1, Q18(b)(ii) (2 marks): The acidic derivative of tartaric acid can be represented by the formula H+K+A2–. Write the equation for the neutralisation of sodium hydrogencarbonate by H+K+A
June 2024, AS Unit 2, Q20(b)(i) (2 marks): Show that myrcene and limonene are terpenes by comparing the molecular and/or empirical formulae of myrcene, limonene and isoprene. myrcene limonene isoprene (2
June 2024, Unit 4, Q15(b)(i) (1 mark): Write an equation for this reaction. State symbols are not required. (1)
June 2024 (R), AS Unit 2, Q5 (1 mark): A gas cylinder contains 2.5 kg of butane. How many molecules of butane are in the cylinder? [Molar mass of butane = 58.0 g mol–1 Avogadro constant, L = 6.02 × 1
June 2024 (R), AS Unit 2, Q22(c)(i) (1 mark): Give the equation for this reaction. State symbols are not required. (1)
June 2024 (R), AS Unit 2, Q22(c)(ii) (1 mark): Name the type of reaction occurring. (1)
June 2024 (R), AS Unit 3, Q5(b)(i) (2 marks): Write an equation to show the reaction taking place in Step B. Include state symbols in your answer. (2)
January 2024, AS Unit 1, Q8 (1 mark): A block of lead measuring 10 cm × 10 cm × 10 cm contains 3.295 × 1025 atoms. Calculate the density of lead. [Ar value: Pb = 207.2 Avogadro constant, L = 6.02 ×
January 2024, AS Unit 1, Q12 (1 mark): A sample of seaweed contains 30.0 mg of iodine per kg. What is the number of iodine atoms in 10 kg of this seaweed? [Ar value: I = 126.9 Avogadro constant L = 6
January 2024, AS Unit 1, Q13 (1 mark): The concentration of sulfur dioxide in a sample of polluted air is 0.4 ppm. What is the percentage of sulfur dioxide molecules in this polluted air? A 0.4% B 0.
January 2024, AS Unit 1, Q20(d)(i) (2 marks): Write an equation for the reaction that occurs. Include state symbols in your answer. (2)
January 2024, AS Unit 2, Q24(a)(iii) (3 marks): SF6 is a potent greenhouse gas. 1.00 g of SF6 absorbs the same amount of infrared radiation as 23.9 kg of CO2 . Calculate the number of molecules of CO2 , to th
January 2024, Unit 5, Q15(a)(i) (1 mark): Give the molecular formula of gingerol. (1)
January 2024, Unit 6, Q3(b)(ii) (1 mark): Write the equation for the generation of sulfur dioxide from the reaction between sodium sulfate(IV) (Na2SO3) and hydrochloric acid. State symbols are not requi
October 2023, AS Unit 1, Q14 (1 mark): The formula of phosgene is COCl2. What is the total number of atoms in 9.9 g of phosgene? [Avogadro constant (L) = 6.02 × 1023 mol–1 Mr value: COCl2 = 99.0] A 1
October 2023, AS Unit 1, Q21(a)(i) (1 mark): Calculate the relative formula mass of basic nickel(II) carbonate, Ni3CO3(OH)4 • 4H2O. (1)
October 2023, AS Unit 1, Q21(a)(iii) (1 mark): Give the reason why use of the term ‘relative molecular mass’ is not appropriate in (a)(i). (1)
October 2023, AS Unit 1, Q21(b)(ii) (1 mark): Write the ionic equation for the formation of basic nickel(II) carbonate from nickel(II) sulfate. State symbols are not required. 3NiSO4(aq) + Na2CO3(aq) + 4NaO
October 2023, AS Unit 2, Q18(a)(i) (1 mark): Write an ionic equation for the neutralisation reaction between aqueous sodium hydroxide and hydrochloric acid. State symbols are not required. (1)
October 2023, AS Unit 2, Q20(a)(i) (2 marks): Carbonate ions may be identified by their reaction with aqueous acid to produce carbon dioxide. Give the ionic equation for this reaction. Include state symbols
June 2023, AS Unit 2, Q22(b)(i) (1 mark): Write the ionic equation for this reaction. State symbols are not required. (1)
June 2023, AS Unit 3, Q1(a)(iii) (1 mark): Give the formula of A. (1)
June 2023, AS Unit 3, Q1(b)(iii) (1 mark): Write the ionic equation for the reaction taking place in (b)(ii). Include state symbols. (1)
June 2023, Unit 5, Q21(c)(i) (2 marks): It is produced in the reaction between Hg(NO3)2 and ethanol. The other products of the reaction are ethanal and water. Write the equation for the reaction of on
June 2023, Unit 5, Q24(b)(iii) (3 marks): A 740 mg tablet of a painkiller contains 4.0 % PVP by mass. Calculate the number of molecules of PVP polymer in the tablet. (3)
January 2023, AS Unit 1, Q1 (1 mark): Which compound contains 2.35 × 1022 molecules in 2.50 g? [Avogadro constant L = 6.02 × 1023 mol–1 Mr values: CO = 28.0 CO2 = 44.0 SO2 = 64.1 SO3 = 80.1] A CO B
January 2023, AS Unit 1, Q5 (1 mark): Which is the equation for the reaction of magnesium chloride solution with sodium hydroxide solution? A Mg+(aq) + OH–(aq) → MgOH(s) B Mg2+(aq) + 2OH–(aq) → Mg(O
January 2023, AS Unit 1, Q25(b) (1 mark): Aluminium trichloride reacts vigorously with water to produce hydrogen chloride and aluminium hydroxide, Al(OH)3. Write the equation for this reaction. State sy
January 2023, AS Unit 2, Q22(a)(iii) (1 mark): Derive the overall equation for the production of H2 in Stage 1. State symbols are not required. (1)
January 2023, AS Unit 2, Q22(b)(ii) (1 mark): Name the type of reaction occurring. (1)
January 2023, AS Unit 3, Q3(b)(i) (1 mark): The unbalanced equation for the reaction between citric acid and sodium hydroxide is shown. H2CCOOH H2CCOONa HOCCOOH + NaOH → HOCCOONa + H2O H2CCOOH H2CCOONa Co
January 2023, Unit 5, Q19(c)(vi) (3 marks): A can of a fizzy drink contains 53 mg of aspartame per 100 cm3 of drink. Calculate the number of molecules of aspartame in a 330 cm3 can of the drink. Give your
October 2022, AS Unit 1, Q2 (1 mark): Which mixture results in a precipitation reaction? A dilute sulfuric acid and potassium hydroxide solution B iron and calcium chloride solution C chlorine water
October 2022, AS Unit 1, Q9 (1 mark): A piece of copper is shown. 4 cm 8 cm 12 cm How many moles of copper atoms are there in this piece of copper? [Density of copper = 8.96 g cm–3] A 0.675 B 1.48 C
October 2022, AS Unit 1, Q14(b)(iii) (1 mark): The barium chloride solution is acidified to prevent carbonate ions giving a false positive result. Write the ionic equation for the reaction of hydrochloric ac
October 2022, AS Unit 2, Q23(a)(i) (1 mark): Write the equation for Step 1. State symbols are not required. (1)
October 2022, AS Unit 3, Q3(b)(v) (1 mark): Deduce the ionic equation for the formation of XI2 , using your answer to (b)(iv). Include state symbols in your answer. (1)
June 2022, AS Unit 1, Q2 (1 mark): A sample of nitrogen gas contains 1.204 × 1022 molecules. What is the mass of this sample? [Ar N = 14.0 Avogadro constant (L) = 6.02 × 1023 mol−1] A 0.14 g B 0.
June 2022, AS Unit 1, Q3 (1 mark): When magnesium oxide reacts with dilute sulfuric acid the equation is MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l) What is the ionic equation for the reaction? A MgO
June 2022, AS Unit 2, Q7 (1 mark): The presence of ammonium ions in a compound can be shown by adding a reagent, warming the mixture and testing the gas evolved. What is the reagent and the resul
January 2022, AS Unit 1, Q7 (1 mark): What is the ionic equation for the reaction between aqueous solutions of barium nitrate and sodium sulfate? A Na+(aq) + NO3 −(aq) ® NaNO3(s) B 2Ba+(aq) + SO4 2−
January 2022, AS Unit 1, Q14 (1 mark): The equation for the complete combustion of hexane is shown. C6H14 + 9½ O2 ® 6CO2 + 7H2O How many molecules of carbon dioxide are formed when 2 × 10−3 mol of he
January 2022, AS Unit 1, Q20(c)(i) (1 mark): Write an equation for the reaction that occurs. State symbols are not required. (1)
January 2022, AS Unit 2, Q16 (1 mark): Barium hydroxide reacts with sulfuric acid as shown. Ba(OH)2(aq) + H2SO4(aq) → BaSO4(s) + 2H2O(l) Which is the ionic equation for this reaction? A Ba2+(aq) + 2O
January 2022, AS Unit 3, Q3(a)(i) (1 mark): Give the ionic equation for the reaction that occurs when sodium sulfate solution is added to the conical flask in Step 2. Include state symbols. (1)
January 2022, Unit 4, Q7 (1 mark): The anti‑inflammatory drug ketoprofen has the structure shown. OH O What is the molecular formula of ketoprofen? A C15H12O3 B C16H13O3 C C16H14O3 D C16H17O3
October 2021, AS Unit 1, Q4(c) (1 mark): The sodium hydroxide solution was neutralised with sulfuric acid. Which is the ionic equation for this reaction? (1) A H+(aq) + OH−(aq) → H2O(l) B SO4 2−(aq) +
October 2021, AS Unit 1, Q7(a) (1 mark): What is the relative formula mass of the double salt? [Ar values: H = 1.0 N = 14.0 O = 16.0 S = 32.1 Fe = 55.8] (1) A 277.9 B 284.0 C 392.0 D 447.8
October 2021, AS Unit 1, Q7(c) (1 mark): What is the total number of ions present in 0.1 mol of the double salt? [Avogadro constant (L) = 6.02 × 1023 mol−1] (1) A 1.80 × 1023 B 2.41 × 1023 C 3.01 × 102
October 2021, AS Unit 1, Q14(d)(i) (1 mark): Aluminium nanoparticles react with water to produce aluminium oxide and hydrogen. Complete the following equation. State symbols are not required. (1) Al + H2O
June 2021, AS Unit 1, Q7 (1 mark): What is the relative formula mass of hydrated sodium carbonate, Na2CO3. 10H2O? [Ar values: H = 1.0 C = 12.0 O = 16.0 Na = 23.0] A 106 B 142 C 263 D 286
June 2021, AS Unit 1, Q20 (1 mark): A sample of seawater with a mass of 1 kg contains 6 × 10−9 g of gold. How many atoms of gold, to one significant figure, are there in 1 g of this seawater? [Ar
January 2021, AS Unit 1, Q1 (1 mark): Which of these compounds has the same empirical and molecular formulae? A C2H4 B C3H8 C C4H10 D C5H10
January 2021, AS Unit 1, Q2 (1 mark): There are 6.02 × 1023 atoms in 0.25 mol of A He B H2O C BH3 D CH4
January 2021, AS Unit 3, Q1(a)(i) (1 mark): The student tested each solution using universal indicator paper. Only solution A turned the paper red. Identify solution A. (1)
January 2021, AS Unit 3, Q1(a)(ii) (1 mark): The student mixed 1 cm3 of solution A separately with 1 cm3 of each of the other solutions. There was no change for three of the mixtures but effervescence was
January 2021, AS Unit 3, Q1(a)(iii) (2 marks): Write an ionic equation for the reaction between solution A and solution C. Include state symbols. (2)
October 2020, AS Unit 1, Q1 (1 mark): What is the empirical formula of butane? A C4H10 B C2H5 C CH2.5 D CnH2n + 2
October 2020, AS Unit 1, Q3 (1 mark): How many molecules are there in 44.0 g of carbon monoxide? Avogadro constant L = 6.02 × 1023 mol–1     Ar values: C = 12.0 O = 16.0 A 3.83 × 1023 B 6.02 ×
October 2020, AS Unit 1, Q5 (1 mark): The formula of barium chloride is BaCl2. Which is correct for barium chloride? [ Ar values: Ba = 137.3 Cl = 35.5 ] A barium chloride exists as a molecule B bari
October 2020, AS Unit 1, Q7 (1 mark): What is the molecular formula of the compound shown? O OH O OH A C2HO2 B C4H2O4 C C4H4O4 D C4H6O4
October 2020, AS Unit 1, Q19(a)(i) (2 marks): Write an equation for the reaction. State symbols are not required. (2)
October 2020, AS Unit 1, Q19(a)(ii) (1 mark): Give a name for this type of reaction. (1)
October 2020, Unit 5, Q25(a) (1 mark): The Lanthanides The lanthanides form a series in the Periodic Table comprising the elements from lanthanum, La (Z = 57) to lutetium, Lu (Z = 71). They have impo
January 2020, AS Unit 1, Q6 (1 mark): What is the relative formula mass of hydrated barium hydroxide, Ba(OH)2.8H2O? [Ar values: Ba = 137.3, O = 16.0, H = 1.0] A 171.3 B 203.3 C 299.3 D 315.3
January 2020, AS Unit 1, Q10(a) (1 mark): What would you see when this reaction is carried out? (1) A blue solution turns colourless B effervescence C no visible change D white precipitate
January 2020, AS Unit 1, Q10(b) (1 mark): What is the ionic equation for this reaction? (1) –(aq) o BaSO4(s) A Ba+(aq) + SO4 B Na+(aq) + Cl–(aq) o NaCl(aq) 2–(aq) o BaSO4(s) C Ba2+(aq) + SO4 2–(aq) + Na
January 2020, AS Unit 1, Q21(a) (2 marks): The global production of ethene is about 150 million tonnes per year. Calculate the number of molecules in 150 million tonnes of ethene. [1 tonne = 1000 kg Avog
June 2019, AS Unit 1, Q7 (1 mark): Which isotope is used as the standard in the definition of relative atomic mass? 1H A 12C B 13C C 16O D
June 2019, AS Unit 1, Q21(a) (1 mark): Complete the equation for this reaction by adding state symbols. (1) MgCO3( ) + 2HCl( ) o MgCl2( ) + H2O( ) + CO2( )
June 2019, AS Unit 1, Q24(a) (1 mark): Write an equation for the decomposition of sodium azide. State symbols are not required. (1)
June 2019, AS Unit 1, Q24(c)(ii) (1 mark): State the type of reaction taking place in reaction B. (1)
June 2019, AS Unit 3, Q1(a) (1 mark): Write the equation for the decomposition of ammonium carbonate. State symbols are not required. (1)
January 2019, AS Unit 1, Q17 (1 mark): Calcium reacts with dilute nitric acid to form calcium nitrate and hydrogen. Which is the balanced equation for this reaction? A Ca + 2HNO3 o Ca(NO3)2 + H2 B Ca
January 2019, AS Unit 1, Q22(b)(ii) (2 marks): Calculate the number of nitrogen atoms in 5.60 g of nitrogen gas. [Avogadro constant = 6.02 × 1023 mol−1] (2)
January 2019, AS Unit 1, Q23(a) (1 mark): Give the empirical formula of 2-methylpropene. (1)
January 2019, AS Unit 1, Q24(a) (2 marks): A precipitate of silver chloride is formed when silver nitrate solution reacts with sodium chloride solution. A student wrote an ionic equation for the reaction

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