Formulae, stoichiometry and the mole concept
14 past-paper questions on Formulae, stoichiometry and the mole concept · examined 2020–2025.
20251 question
8 Aluminium ions, A l 3+ , react with sulfate ions, SO4 2– , to form aluminium sulfate. Which row shows the correct empirical formula and ionic formula of aluminium sulfate? empirical formula ionic formula A A l SO4 A l 3+ SO4 2– B A l 2S2O8 A l 3+ (SO4 2– )2 C A l 2S3O12 A l 3+ 2(SO4) 2– 3 D A l 3S2O8 A l 2+ 3(SO4 3– )2
20232 questions
© UCLES 2023 5070/11/M/J/23 8 Two aqueous solutions, Q and R, have the same concentration in mol / dm . Solution Q contains 4.0 g of NaOH in 500 cm 3 of solution. Which solution could be solution R? [ A r: Na, 23; O, 16; H, 1] A 0.2 mol of Ca(OH)2 in 250 cm 3 of solution B 0.2 mol of HC l in 100 cm 3 of solution C 0.05 mol of H2SO4 in 250 cm 3 of solution D 0.1 mol of KOH in 1000 cm 3 of solution 5
5070/21/O/N/23 © UCLES 2023 50 100 150 200 time / s 250 300 350 0 10 20 30 40 50 60 volume of hydrogen / cm 3 Fig. 3.1 (i) Deduce the time taken from the beginning of the experiment to collect 39 cm 3 of hydrogen. time ....................................................... s [1] (ii) The student repeats the experiment using dilute hydrochloric acid with a higher concentration. All other conditions stay the same. Draw a line on the grid in Fig. 3.1 to show how the volume of hydrogen changes when dilute hydrochloric acid with a higher concentration is used. [2] 7 5070/21/O/N/23 © UCLES 2023 [Tu
20222 questions
7 Two isotopes of chlorine are C l and C l . Using these isotopes and 12 C and 1 H, how many different relative molecular masses are possible for the compound with molecular formula C2H3C l 3? A 2 B 3 C 4 D 5
5070/21/O/N/22 © UCLES 2022 6 This question is about compounds of nitrogen. (a) The equation represents the equilibrium between N 2 O 4 and NO 2 at a high temperature in a closed container. N 2 O 4 (g) 2NO 2 (g) (i) Predict what happens to the position of equilibrium when the pressure is decreased. Explain your answer. prediction ........................................................................................................................... explanation ........................................................................................................................ ...........
20213 questions
9 The empirical formula of compound X is CH2 and the relative molecular mass, M r, of X is 70. What is the molecular formula of X? A CH2 B C2H4 C C5H10 D CnH2n
© UCLES 2021 5070/11/M/J/21 10 A chemist wants to make calcium nitrate. They start with 8.00 g of pure calcium oxide and an excess of dilute nitric acid. They produce 12.65 g of pure, dry anhydrous calcium nitrate crystals. What is the percentage yield of calcium nitrate? [relative atomic masses, A r: Ca, 40; N, 14; H, 1; O, 16] A 54.0 B 63.2 C 67.1 D 86.8 5
© UCLES 2021 5070/11/M/J/21 [Turn over 18 Which changes will speed up a chemical reaction? 1 decreasing the pressure in a reaction between gases 2 increasing the size of the solid particles in a reaction involving solids 3 increasing the temperature of any reaction 4 increasing the concentration of a solution A 1 and 3 B 2, 3 and 4 C 3 and 4 only D 4 only 8
You're viewing 8 of 14 questions
Free members see the first 8. Join Learning DEN Pro to unlock all 14 questions on this chapter — plus AI topical search, downloadable topical PDF packs, and examiner marking on any answer. From $9/month.
Don't just read the solution — get your own answer marked
Write your answer to any Chemistry past-paper question, photograph it, and Learning DEN marks it like a real examiner — marks awarded, where you lost them, and your predicted grade. 3 free gradings to start.