Formulae, equations and amount of substance: OCR A‑Level Chemistry B questions

Every OCR A-Level Chemistry B exam question on EL Formulae, equations and amount of substance (specification points EL(a)–(d)), 2016–2025, with its mark scheme and examiner’s report.

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2,049 questions

Q19
June 2025 · Paper 1
1 markEL Formulae, equations and amount of substance
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Q33(a)
June 2025 · Paper 1
2 marksEL Formulae, equations and amount of substance
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Q2(f)
June 2025 · Paper 2
2 marksEL Formulae, equations and amount of substance
The whole paper ↗
Q4(b)
June 2025 · Paper 3
6 marksEL Formulae, equations and amount of substance
The whole paper ↗
Q12
June 2025 · AS Paper 1
1 markEL Formulae, equations and amount of substance
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Q19
June 2025 · AS Paper 1
1 markEL Formulae, equations and amount of substance
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Q24(d)(iii)
June 2025 · AS Paper 1
3 marksEL Formulae, equations and amount of substance
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Q3(c)
June 2025 · AS Paper 2
6 marksEL Formulae, equations and amount of substance
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Q3(d)(i)
June 2025 · AS Paper 2
3 marksEL Formulae, equations and amount of substance
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Q3(d)(ii)
June 2025 · AS Paper 2
1 markEL Formulae, equations and amount of substance
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Q3(d)(iii)
June 2025 · AS Paper 2
3 marksEL Formulae, equations and amount of substance
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Q4(c)(i)
June 2025 · AS Paper 2
2 marksEL Formulae, equations and amount of substance
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Q4(c)(ii)
June 2025 · AS Paper 2
2 marksEL Formulae, equations and amount of substance
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Q4(e)
June 2025 · AS Paper 2
1 markEL Formulae, equations and amount of substance
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Q1
June 2024 · Paper 1
1 markEL Formulae, equations and amount of substance
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Q31(e)(i)
June 2024 · Paper 1
2 marksEL Formulae, equations and amount of substance
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Q31(e)(ii)
June 2024 · Paper 1
5 marksEL Formulae, equations and amount of substance
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Q31(e)(iii)
June 2024 · Paper 1
1 markEL Formulae, equations and amount of substance
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Q1(e)(i)
June 2024 · Paper 2
2 marksEL Formulae, equations and amount of substance
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Q2(c)(i)
June 2024 · Paper 2
3 marksEL Formulae, equations and amount of substance
The whole paper ↗

All 149 questions on Formulae, equations and amount of substance, as a list

June 2025, Paper 1, Q19 (1 mark): 2.00 g of an oxide of copper contains 1.78 g of copper. What is the oxidation state of the copper in the oxide? A –1 B 0 C +1 D +2 Your answer [1]
June 2025, Paper 1, Q33(a) (2 marks): The student uses an incorrect method for measuring the mass of ammonium nitrate. Explain what the student should do to correctly measure the mass of ammonium ni
June 2025, Paper 2, Q2(f) (2 marks): Another oxide of nitrogen contains 37% nitrogen by mass. Calculate the formula of the oxide. Formula = [2]
June 2025, Paper 3, Q4(b) (6 marks): This question ref ers to the Practical Insert that is provided with this paper. – in a beaker. (b)* At the end of Part 1 of their method, the students have a so
June 2025, AS Paper 1, Q12 (1 mark): Sodium hydroxide reacts with sulfuric acid: 2NaOH + H2SO4 Na2SO4 + 2H2O What volume (in cm3) of 0.1 mol dm–3 NaOH will neutralise 15 cm3 of 0.2 mol dm–3 H2SO4?
June 2025, AS Paper 1, Q19 (1 mark): 25 cm3 of 0.10 mol dm–3 silver nitrate solution reacts with an excess of a sodium halide solution to form 0.59 g of silver halide precipitate. Which halide is r
June 2025, AS Paper 1, Q24(d)(iii) (3 marks): Calculate the volume (in cm3) of 0.24 mol dm–3 NaIO3 solution that would react with 15 g of NaI in Equation 24.1. Give your answer to an appropriate number of s
June 2025, AS Paper 2, Q3(c) (6 marks): A student investigates the reactions of some of the elements and compounds of Group 2. (c)* A batch of Na2SO3 has partially oxidised to Na2SO4. Two students eac
June 2025, AS Paper 2, Q3(d)(i) (3 marks): Plot a graph of mass of water against mass of hydrated salt on the graph paper below. Include the origin. Draw a line of best fit. [3]
June 2025, AS Paper 2, Q3(d)(ii) (1 mark): Identify the anomalous point and suggest what caused this anomaly. Anomalous point Suggested cause of anomaly [1]
June 2025, AS Paper 2, Q3(d)(iii) (3 marks): Calculate the value of x in the formula MgSO4•xH2O. Use the results from Student C. x = [3]
June 2025, AS Paper 2, Q4(c)(i) (2 marks): used. Amount of ethanol = mol [2]
June 2025, AS Paper 2, Q4(c)(ii) (2 marks): The student then uses a 1.00 cm3 volumetric pipette to transfer 1.00 cm3 of the mixture to a conical flask containing 100 cm3 of ice-cold water. The student tit
June 2025, AS Paper 2, Q4(e) (1 mark): Suggest why the student uses a 1.00 cm3 volumetric pipette and not a small measuring cylinder for transferring 1.00 cm3 of the equilibrium mixture for the titra
June 2024, Paper 1, Q1 (1 mark): An isotope of an element has a mass number of 25. What is correct for an atom of this isotope? A It has 12 neutrons. B It has 25 electrons. C It has 25 protons.
June 2024, Paper 1, Q31(e)(i) (2 marks): Describe the procedure they should use for weighing out the 3.02 g of MCO3. [2]
June 2024, Paper 1, Q31(e)(ii) (5 marks): Calculate the Mr of MCO3. Mr = [5]
June 2024, Paper 1, Q31(e)(iii) (1 mark): The 25.0 cm3 of the solution used for the titration is measured using a volumetric pipette. The uncertainty in reading the volumetric pipette is 0.06 cm3. Calcu
June 2024, Paper 2, Q1(e)(i) (2 marks): The iodine value of a fat or carboxylic acid is the mass of iodine that will combine with 100 g of the substance, saturating the double bonds. Calculate the iod
June 2024, Paper 2, Q2(c)(i) (3 marks): When 5.6 g of FeSO4•xH2O is heated gently, 3.1 g of FeSO4 is left. Calculate the value of x in FeSO4•xH2O, where x is a whole number. x = [3]
June 2024, Paper 2, Q2(c)(ii) (3 marks): When FeSO4 is heated more strongly, a brown solid (Mr = 159.6) remains and two acidic gases are formed. Suggest an equation for this reaction. Give your reasoni
June 2024, Paper 2, Q5(a)(iv) (3 marks): The article says: ‘A single gram of freon will often destroy as much as 70 kg of ozone.’ Calculate how many ozone molecules are destroyed by one Cl radical if 1
June 2024, Paper 3, Q2(e) (3 marks): The students start with 0.90 g aspirin with the other reactants in excess. After the reaction, they collect 0.70 g of the purified oil of wintergreen. Calculate
June 2024, Paper 3, Q3(d) (4 marks): The ‘Dead Sea’ is a lake that contains much more bromide than ‘normal’ sea water. Water from the Dead Sea is used to produce bromine. Some data about water from
June 2024, AS Paper 1, Q1 (1 mark): On a Periodic Table the number 39.1 is shown for potassium, K. What is this number? A atomic number B mass number C relative atomic mass D relative molecular ma
June 2024, AS Paper 1, Q11 (1 mark): Aluminium reacts with chlorine to form Al Cl 3. What is the maximum mass (in g) of Al Cl 3 (Mr = 133.5) that could be made by reacting 5.4 g of aluminium with 1
June 2024, AS Paper 1, Q23(c) (3 marks): Calculate the minimum mass of CO needed to make 15 g of ethanoic acid by the Cativa process. Give your answer to an appropriate number of significant figures. m
June 2024, AS Paper 2, Q1(c)(i) (3 marks): Calculate the percentage by mass of chlorine in the unknown solid. percentage by mass of chlorine = % [3]
June 2024, AS Paper 2, Q1(c)(ii) (2 marks): The student fails to dry the AgCl precipitate fully. What effect would this have on the percentage by mass of chlorine calculated? Explain your answer. [2]
June 2024, AS Paper 2, Q3(h) (6 marks): Most diesel fuel is made from crude oil. However, biodiesel, made from vegetable oils, is increasingly being used. (h)* An organic compound A, has the following
June 2023, Paper 1, Q20 (1 mark): 10 cm3 of 0.30 mol dm–3 AgNO3 is mixed with 20 cm3 of 0.10 mol dm–3 NaCl . What is the maximum mass (in grams) of silver chloride (Mr = 143) that could be forme
June 2023, Paper 1, Q25 (1 mark): A student records the following readings for a titration: Trial 1 2 3 2nd burette reading / cm3 20.45 40.80 40.45 20.50 1st burette reading / cm3 0.20 20.50 20.
June 2023, Paper 1, Q33(a)(i) (2 marks): Calculate the percentage yield in this salt preparation. percentage yield = % [2]
June 2023, Paper 2, Q1(e) (4 marks): The students have another solution containing 20 g dm–3 bromine. They find that 160 cm3 of this solution reacts exactly with 0.80 g of a hydrocarbon with a mole
June 2023, Paper 2, Q2(b)(ii) (2 marks): The students use 14 g of both compound A and compound B. Calculate the amounts of each (in mol) that show that compound B is in excess. amount of compound A = m
June 2023, Paper 2, Q2(b)(iii) (3 marks): The students recrystallise their crude phenacetin using water and obtain 20 g of solid product. They calculate their percentage yield. What advice would you giv
June 2023, Paper 2, Q4(b) (2 marks): A concentration of greater than 6 × 10–4 mol dm–3 of ketone bodies in the bloodstream is known as ‘ketosis’. Calculate the mass of propanone (Mr 58) (in grams)
June 2023, Paper 2, Q5(d)(ii) (2 marks): Impure calcium carbide contains calcium phosphide. The phosphide ion is P3–. Calcium phosphide reacts with water to form PH3. Suggest a chemical equation for th
June 2023, AS Paper 1, Q17 (1 mark): What is the Avogadro constant, NA, the number of? A Atoms in one mole of carbon dioxide. B Carbon atoms in one mole of C2H5OH. C Sodium ions in one mole of NaCl
June 2023, AS Paper 1, Q21(a)(i) (1 mark): Explain the meaning of heating to constant mass. [1]
June 2023, AS Paper 1, Q21(a)(ii) (3 marks): On the grid below, plot a graph of the results in Table 21.1. Include the origin. Draw the line of best fit. [3]
June 2023, AS Paper 1, Q21(a)(iii) (3 marks): Plaster of Paris has the formula CaSO4•xH2O. Calculate the value of x in this formula. Give your answer to 1 significant figure. x = [3]
June 2023, AS Paper 2, Q1(d) (4 marks): A student is provided with a solid sample of an unknown Group 2 hydroxide, X(OH)2. The student describes how 250 cm3 of a solution of this solid is made up in a
June 2023, AS Paper 2, Q1(e) (6 marks): This question is about Group 2 compounds. Group 2 hydroxides can be used to neutralise acidity in a variety of contexts. Magnesium hydroxide may be used to neut
June 2023, AS Paper 2, Q3(c)(i) (3 marks): Calculate the percentage yield of aspirin in this preparation. percentage yield = % [3]
June 2023, AS Paper 2, Q4(d) (2 marks): Ammonia can be converted into the fertiliser ammonium nitrate by reaction with nitric acid, as shown in Equation 4.3. NH3 + HNO3 NH4NO3 Equation 4.3 Calculate t
June 2022, Paper 2, Q1(h)(i) (1 mark): What is meant by the term mass number? [1]
June 2022, Paper 2, Q5(c) (1 mark): SnF2 is said in the article to hydrolyse at ‘higher pH’. Suggest an equation for the reaction between SnF2 and hydroxide ions. [1]
June 2022, Paper 3, Q2(a)(i) (2 marks): The student adds 1.20 g of powdered zinc to 50.0 cm3 of 0.200 mol dm–3 copper(II) sulfate solution in a glass beaker. Use calculations to show which is the limi
June 2022, Paper 3, Q4(a) (3 marks): Suggest how the students accurately made up a solution of 0.300 mol dm–3 copper(II) nitrate from their standard 0.400 mol dm–3 solution. Name the apparatus invo
June 2022, AS Paper 1, Q13 (1 mark): What mass of Na2CO3 is needed to make up 250 cm3 of a 0.100 mol dm–3 solution? (Na, 23; C, 12; O, 16) A 2.65 g B 3.57 g C 10.6 g D 26.5 g Your answer [1]
June 2022, AS Paper 1, Q23(c)(iv) (1 mark): The students are told that they should have used a volumetric pipette rather than a measuring cylinder to measure out 25 cm3 of bleach. What effect would this h
June 2022, AS Paper 2, Q2(d) (3 marks): A CFC has the following percentage composition by mass: C, 11.7%; F, 18.8%; Cl, 69.5%. The relative molecular mass of this CFC is 204. Calculate the molecular f
November 2021, Paper 1, Q1 (1 mark): Chlorine-35 is an isotope of chlorine. What is correct about an atom of chlorine-35? A It has 35 electrons. B It has 35 neutrons. C It has 35 protons. D It has
November 2021, Paper 1, Q2 (1 mark): What is meant by ‘heating to constant mass’? A Heating a sample for a long time. B Heating a sample, then weighing, then heating and weighing again several time
November 2021, Paper 1, Q20 (1 mark): The iodine number of an oil is a measure of its unsaturation. The iodine number is the mass of iodine that will react with 100 g of the oil. What is the iodine
November 2021, Paper 1, Q25 (1 mark): A student has 50 cm3 of a 0.25 mol dm–3 solution. What volume of water (in cm3) should the student add to get a 0.10 mol dm–3 solution? A 2.5 B 20 C 75 D 125 Yo
November 2021, Paper 1, Q31(c)(ii) (5 marks): The students make up a solution containing 6.58 g of fertiliser in 0.250 dm3 of deionised water. 25.0 cm3 of this solution needs 15.50 cm3 of 0.200 mol dm–3 bar
November 2021, Paper 2, Q1(g) (3 marks): A hydrocarbon is completely burned. 11 g of carbon dioxide and 6.0 g of water are formed. Calculate the empirical formula of the hydrocarbon. formula [3]
November 2021, Paper 2, Q2(e) (2 marks): The students are given a sample of 5.0 g of rust with the formula Fe2O3•2H2O. The students heat the rust and find that it loses 1.0 g. Show by calculation wheth
November 2021, Paper 2, Q3(e)(iii) (3 marks): In an experiment, 5.0 g of benzaldehyde gives 6.3 g of mandelic acid. Calculate the percentage yield. yield = % [3]
November 2021, Paper 2, Q5(g)(ii) (2 marks): The Article says that one form of indium tin oxide has percentages by mass: 53% In, 28% Sn and 19% O. Show how the percentages by mass are related to the formul
November 2021, AS Paper 1, Q21(b)(i) (1 mark): The high Mr of BaSO4 makes it absorb X-rays well, compared with CaSO4. Give the Mr values of CaSO4 and BaSO4. CaSO4 BaSO4 [1]
November 2021, AS Paper 1, Q22(a)(ii) (2 marks): Which reagent is in excess? Show your calculations. reagent in excess is [2]
November 2021, AS Paper 2, Q2(c) (4 marks): A student wishes to determine the concentration of a sample of hydrochloric acid by titrating the acid with a standard solution of sodium carbonate. The student
November 2021, AS Paper 2, Q2(d)(i) (3 marks): A student titrates 25.0 cm3 of a solution of sodium carbonate with 0.100 mol dm–3 hydrochloric acid in order to find the concentration of the sodium carbonate.
November 2021, AS Paper 2, Q2(d)(ii) (4 marks): Another student is asked to determine the value of x in hydrated sodium carbonate, Na2CO3•xH2O. The student dissolves 1.46 g of the hydrated salt in water and m
November 2020, Paper 1, Q32(b) (3 marks): The concentration of bromide ions in water from the Dead Sea is 5 g dm−3. Calculate the number of bromide ions in 1 cm3 of Dead Sea water. Give your answer to a
November 2020, Paper 1, Q35(b) (3 marks): The students first dilute the seawater by pipetting 20.0 cm3 of seawater into a 100 cm3 volumetric flask and making up to the mark with deionised water. 25.0 cm
November 2020, Paper 2, Q2(d)(iii) (3 marks): The students are told that in a standard IO3 They plan to prepare 40 cm3 of the solution for the electrode by mixing 20 cm3 of 0.08 mol dm−3 I2(aq) with 20 cm3
November 2020, Paper 2, Q3(b) (2 marks): KH2PO4 when used in fertilisers is said to be equivalent to 52% P2O5 and 34% K2O by mass. Show that the mole ratio of potassium to phosphorus in 52% P2O5 and 34
November 2020, Paper 2, Q4(a)(ii) (3 marks): A solution has 2.32 g dm−3 of maleic acid. Calculate the volume (in cm3) of 2.0 mol dm−3 NaOH(aq) that would completely neutralise 250 cm3 of the solution. volu
November 2020, Paper 2, Q4(b)(i) (1 mark): Give the empirical formula of both acids. [1]
November 2020, Paper 3, Q1(c)(i) (1 mark): Explain the term ‘heat to constant mass’. [1]
November 2020, Paper 3, Q1(c)(ii) (3 marks): 4.00 g of a metal carbonate MCO3 gives 1.91 g of MO on heating to constant mass. Identify metal M in MCO3 showing a suitable calculation. metal M is [3]
November 2020, Paper 3, Q2(c) (4 marks): A student followed the procedure in the flow chart and obtained 5.46 g of methyl benzoate. The equation for the preparation is: C6H5COOH + CH3OH C6H5COOCH3 + H2
November 2020, AS Paper 1, Q19 (1 mark): A student measures a volume of 200 cm3. What is the best way to express the number ‘two hundred’ to two significant figures? A 200 B 200.00 2.0 × 102 C 2.00 × 1
November 2020, AS Paper 1, Q20 (1 mark): A student is doing a titration. The student measures a titre of 21.5 cm3. How can the student decrease the uncertainty in the burette readings? A Repeat the tit
November 2020, AS Paper 1, Q23(c) (2 marks): Calcium chloride is added to lower the melting temperature of sodium chloride. The electrolyte often contains 33% NaCl and 67% CaCl 2 by mass. Calculate the num
November 2020, AS Paper 2, Q2(a) (2 marks): Write an equation for the reaction of solid barium carbonate with hydrochloric acid. Carbon dioxide is produced in the reaction. Include state symbols. [2]
November 2020, AS Paper 2, Q2(d)(i) (1 mark): The uncertainty in using a 25.0 cm3 pipette is 0.06 cm3. Calculate the percentage uncertainty in using this pipette. percentage uncertainty = % [1]
November 2020, AS Paper 2, Q2(d)(ii) (4 marks): The student titrates the 25.0 cm3 of saturated Ca(OH)2 with hydrochloric acid of concentration 0.100 mol dm−3. Ca(OH)2 + 2HCl CaCl 2 + 2H2O A mean titre of 11.7
November 2020, AS Paper 2, Q3(b)(ii) (3 marks): The student reacts 3.5 g of 4-hydroxybenzoic acid with an excess of ethanoic anydride. After purifying the crude product the student obtains 2.8 g of 4-acetoxyb
June 2019, Paper 1, Q1 (1 mark): Which statement about an atom of 23Na is correct? 1 A It is an isomer of sodium. B It has an atomic number of 23. C It has 12 neutrons in its nucleus. D It has
June 2019, Paper 1, Q19 (1 mark): When all the water is driven off from 11.89 g of NiCl2•xH2O, the residue weighs 6.49 g. What is the value of x? A 2 B 3 C 4 D 6 Your answer [1]
June 2019, Paper 1, Q20 (1 mark): A student adds 10 cm3 of water to 12 cm3 of a 0.010 mol dm–3 solution. What is the resulting concentration in mol dm–3? A 0.0045 B 0.0055 C 0.0083 D 0.018 Your
June 2019, Paper 1, Q26 (1 mark): 0.125 mol of CuO is reacted with excess sulfuric acid and the solution allowed to crystallise. What mass of hydrated copper sulfate, CuSO4•5H2O, is formed if th
June 2019, Paper 2, Q1(c) (2 marks): Compound A can be made by the reaction in Fig. 1.2. O O O O + 2SOCl2 + 2HCl + 2SO2 HO OH Cl Cl benzene-1,4-dicarboxylic acid compound A Fig. 1.2 Calculate the m
June 2019, Paper 2, Q2(c)(i) (1 mark): How many neutrons are there in an atom of 84Sr? number of neutrons = [1]
June 2019, Paper 2, Q2(d) (6 marks): Strontium carbonate is used in fireworks to colour the flames red. (d)* Strontium oxide reacts with water to form strontium hydroxide, Sr(OH)2. The solubility o
June 2019, Paper 3, Q2(f) (3 marks): The students then recrystallised their paracetamol sample. The students started with a mass of 2.1 g of 4-aminophenol and used excess ethanoic anhydride. The ma
June 2019, AS Paper 1, Q10 (1 mark): Urea has formula CO(NH2)2. What is the percentage of nitrogen by mass in urea? A 23% B 25% C 41% D 47% Your answer [1]
June 2019, AS Paper 1, Q22(c)(i) (1 mark): Write the equation for the reaction in the titration. [1]
June 2019, AS Paper 1, Q22(c)(ii) (2 marks): Calculate the concentration of Ba(OH)2 in mol dm–3. concentration = mol dm–3 [2]
June 2019, AS Paper 1, Q22(c)(iii) (1 mark): Calculate the concentration of Ba(OH)2 in g dm–3. concentration = g dm–3 [1]
June 2019, AS Paper 2, Q2(f)(ii) (3 marks): A solution of sodium bromide has a concentration of 0.0260 mol dm–3. 25.0 cm3 of this solution are mixed with an excess of silver nitrate solution. 0.118 g of s
June 2019, AS Paper 2, Q4(b) (2 marks): An alternative halon that is also used in fire extinguishers has the following composition by mass. C Br F 9.2% 61.5% 29.3% The Mr of this halon is 259.8. Deduc
June 2018, Paper 1, Q17 (1 mark): An unsaturated carboxylic acid has an Mr of 280. 70 g of the acid is saturated by 1.0 g of hydrogen. How many C=C bonds are there in one molecule of the acid? A
June 2018, Paper 1, Q18 (1 mark): Sodium carbonate reacts with hydrochloric acid as shown in the equation. Na2CO3 + 2HCl 2NaCl + CO2 + H2O What mass (in grams) of Na2CO3 will react exactly with
June 2018, Paper 1, Q31(a) (3 marks): In a cracking reaction 1.50 tonnes of dodecane (C12H26) produce 478 kg of hexane (C6H14). Calculate the percentage yield of the reaction in equation 31.1. perce
June 2018, Paper 1, Q35(a) (2 marks): Describe how the chemists would dissolve one bolt and make the solution up to 1.00 dm3. [2]
June 2018, Paper 1, Q36(f)(ii) (4 marks): The overall yield of the reactions in equations 36.4 – 36.6 is 77%. The yield of ammonium nitrate in equation 36.7 can be taken as 100%. What mass (in tonnes) o
June 2018, Paper 2, Q1(b) (2 marks): Some students heat a sample of MgCO3•3H2O to try to make MgCO3. Calculate the percentage loss in mass they will obtain if they succeed. percentage loss in mass
June 2018, Paper 2, Q2(c)(ii) (2 marks): What mass of propene (in kg) would be obtained from 15 kg of nonane in the reaction in (i) if the percentage yield was 85%? mass of propene = kg [2]
June 2018, Paper 2, Q3(g) (2 marks): The students have 20.0 cm3 0.35 mol dm−3 H2O2 and wish to make a 0.05 mol dm−3 solution. How much water should they add? volume of water to add = cm3 [2]
June 2018, Paper 2, Q5(c) (2 marks): Write an equation for the reaction of a solution of As3+ with hydrogen sulfide. Show state symbols. [2]
June 2018, Paper 3, Q4(a)(ii) (3 marks): Use the student results to calculate the percentage yield of phenyl benzoate obtained from the practical. percentage yield = % [3]
June 2018, AS Paper 1, Q9 (1 mark): What is the percentage of chlorine by mass in magnesium chloride? A 59% B 66% C 74% D 75% Your answer [1]
June 2018, AS Paper 1, Q14 (1 mark): 35 cm3 of a solution has a concentration of 0.125 mol dm–3. A student calculates the amount (in moles) of solute in this solution. Which answer is given to the
June 2018, AS Paper 1, Q15 (1 mark): Hydrochloric acid reacts with sodium carbonate as shown in the equation. 2HCl + Na2CO3 2NaCl + CO2 + H2O 20 cm3 of 2.0 mol dm–3 Na2CO3 are added to 20 cm3 2.0 m
June 2018, AS Paper 1, Q21(b)(ii) (1 mark): The density of ethanoic anhydride is 1.1 g cm–3. Calculate the amount (in moles) of ethanoic anhydride used. amount of ethanoic anhydride = mol [1]
June 2018, AS Paper 1, Q21(b)(iii) (2 marks): Which is in excess, the salicylic acid or the ethanoic anhydride? [2]
June 2018, AS Paper 1, Q21(d) (2 marks): After recrystallisation, the students obtained 3.1 g of aspirin. What value for the percentage yield does this give? yield = % [2]
June 2018, AS Paper 2, Q1(d) (6 marks): Chemists have arranged the elements into a Periodic Table which allows them to make predictions about the behaviour of the elements and their compounds. (d)* A
June 2017, Paper 1, Q1 (1 mark): What is a possible mass number of a magnesium isotope? A 12 B 23.99 C 24 D 24.3 Your answer [1]
June 2017, Paper 1, Q23 (1 mark): 5.6 g of Fe (Ar = 56) and 4.0 g of S (Ar = 32) are heated in air until no further reaction occurs. All the iron is converted to FeS and the rest of the sulfur f
June 2017, Paper 1, Q24 (1 mark): A student has 25 cm3 of a 0.014 mol dm–3 solution. How much water should be added to make the solution 0.010 mol dm–3? 10 cm3 A 14 cm3 B 35 cm3 C 49 cm3 D Your
June 2017, Paper 1, Q31(b) (3 marks): A sodium chloride solution contains 24.0% of sodium chloride by mass. 1.0 tonne of this solution is electrolysed. Calculate the mass of chlorine produced (in to
June 2017, Paper 1, Q35(a) (6 marks): Magnesium sulfate, MgSO4, has a variety of uses in agriculture and in medicine. It exists in the solid state as a hydrated salt, MgSO4•xH2O. In order to find th
June 2017, Paper 2, Q1(a)(ii) (2 marks): Calculate the volume (in cm3) of 0.500 mol dm–3 Na2CO3 that would react with 25.0 cm3 of 0.450 mol dm–3 CH3COOH. volume of Na2CO3 = cm3 [2]
June 2017, Paper 2, Q2(b)(i) (2 marks): The students want to make 5.0 g of 4-nitrophenol in step 1. Calculate the mass of phenol they should start with. Give your answer to an appropriate number of si
June 2017, Paper 2, Q4(a)(ii) (2 marks): Calculate the maximum mass of chromium (in kg) that could be obtained from 1000 g of chromite. mass = kg [2]
June 2017, Paper 3, Q2(a)(ii) (3 marks): 50 cm3 acid is used each time. The concentration ranged from 0.1 to 0.5 mol dm–3. Calculate the maximum mass of magnesium ribbon that would completely react wit
June 2017, Paper 3, Q2(a)(iii) (1 mark): Calculate the maximum length of magnesium ribbon needed to completely react with the acid in all the experiments. The mass per unit length of Mg ribbon = 1.3 ×
June 2017, Paper 3, Q4 (15 marks): (a) (i) Name the piece of apparatus which is most suitable for removing the 25.0 cm3 of the 4 Cu2+ ion solution. [1] (ii) Use the student’s results in the Pract
June 2017, AS Paper 1, Q1 (1 mark): How many hydrogen atoms are there in 1 mol of methanol? A 3 B 4 1.8 × 1024 C 2.4 × 1024 D [1] Your answer
June 2017, AS Paper 1, Q22(c)(i) (1 mark): Write a full equation for the reaction that occurs. [1]
June 2017, AS Paper 1, Q22(d)(i) (2 marks): 25.0 cm3 of the Na2CO3 solution requires 23.6 cm3 of HCl. Calculate the concentration of the HCl. concentration = mol dm–3 [2]
June 2017, AS Paper 1, Q22(d)(ii) (2 marks): A student says: ‘There is no point writing 0.150 mol dm–3 for the Na2CO3 solution. Writing 0.15 mol dm–3 means the same thing.’ Discuss whether or not the stude
June 2017, AS Paper 1, Q22(f)(i) (1 mark): Describe how the students could ensure that all the water had been lost. [1]
June 2017, AS Paper 1, Q22(f)(ii) (2 marks): Calculate the value of x. x = [2]
June 2017, AS Paper 2, Q3(a)(i) (1 mark): Calculate the amount (in moles) of NaOH in 0.50 tonne of sodium hydroxide. amount of NaOH = mol [1]
June 2017, AS Paper 2, Q3(a)(ii) (1 mark): Calculate the mass of chlorine (in tonnes) produced at the same time as 0.50 tonne of sodium hydroxide. mass = tonnes [1]
June 2017, AS Paper 2, Q4(c)(i) (1 mark): Explain why the appropriate mean titre for this titration is 20.85 cm3. [1]
June 2017, AS Paper 2, Q4(c)(ii) (1 mark): The student uses a burette that can be read to the nearest 0.05 cm3. Calculate the percentage uncertainty in the titre of 20.80 cm3. percentage uncertainty = %
June 2017, AS Paper 2, Q4(c)(iii) (3 marks): The equation for the reaction between calcium hydroxide and hydrochloric acid is shown below. Ca(OH)2(aq) + 2HCl(aq) CaCl2(aq) + 2H2O(l) Calculate the concentra
June 2017, AS Paper 2, Q4(d) (1 mark): The elements in a modern Periodic Table are arranged by atomic number. Explain the meaning of the term atomic number. [1]
June 2016, AS Paper 1, Q18 (1 mark): Some students wish to make 0.970 mol of zinc oxide by the reaction shown below. They are told that the reaction gives a 95.0% yield. ZnCO3(s) ZnO(s) + CO2(s) Wh
June 2016, AS Paper 1, Q19 (1 mark): Which solution contains the greatest number of ions? 10.0 cm3 of 0.500 mol dm−3 NaCl A 0.300 dm3 of 0.0400 mol dm−3 NaCl B 0.0200 dm3 of 0.500 mol dm−3 MgCl2 C
June 2016, AS Paper 1, Q22(d)(ii) (1 mark): Write an equation, using molecular formulae, for the reaction of isobutylene with methanol. [1]
June 2016, AS Paper 2, Q2(b) (3 marks): Calculate the amount (in mol) of Mg(OH)2 in a bottle containing 250 cm3 at 8.0% w/v. Give your answer to two significant figures. amount of Mg(OH)2 = mol [3]
June 2016, AS Paper 2, Q2(c)(ii) (1 mark): Suggest why it is not easy to use a direct titration in this situation. [1]
June 2016, AS Paper 2, Q2(d)(i) (1 mark): Explain why the student should use 16.65 cm3 as the mean titre. [1]
June 2016, AS Paper 2, Q2(d)(ii) (2 marks): The equation for the titration is shown below. 2NaOH + H2SO4 Na2SO4 + 2H2O Calculate the amount (in mol) of the H2SO4 in excess. amount of H2SO4 in excess = mol
June 2016, AS Paper 2, Q2(d)(iii) (3 marks): Calculate the mass of Mg(OH)2 in 250 cm3 of milk of magnesia. The equation for the reaction of sulfuric acid with magnesium hydroxide is shown below. Mg(OH)2 +
June 2016, AS Paper 2, Q2(d)(iv) (1 mark): The uncertainty associated with the use of a class B pipette is 0.06 cm3. Calculate the percentage uncertainty associated with using this pipette to measure the
June 2016, AS Paper 2, Q3(e) (2 marks): Student B prepares 0.68 g pure aspirin starting with 1.15 g of 2-hydroxybenzoic acid. Calculate student B’s percentage yield of pure aspirin. percentage yield o
June 2016, AS Paper 2, Q4(d)(ii) (1 mark): The gaseous products of the reaction are cooled to room temperature. Calculate the percentage of the products (by mass) that remain gaseous. % by mass of produc
June 2016, AS Paper 2, Q4(e) (6 marks): Ethanoic acid is an important chemical intermediate in the manufacture of a wide range of products. It was originally made by oxidising ethanol. (e)* An alcohol

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