2024 XMS SEC4 WA1 QP

3 6092/Chemistry/2024 Term 1 Weighted Assessment Section A Answer all questions. Write your answers in the boxes provided at the end of the Section. 1 What is the empirical formula of a gas that contains 50% by mass of sulfur and 50% by mass of oxygen? A SO B SO2 C SO3 D S2O 2 What is the maximum mass of chromium metal, Cr that can be extracted from 76 kg of chromium(III) oxide, Cr2O3? The equation is shown below: 2Cr2O3 → 4Cr + 3O2 A 24 kg B 48 kg C 52 kg D 104 kg 3 Molecules of hydrogen (H 2) and chlorine (C l2) are produced when hydrogen chloride (HC l) decomposes. The equation for the decomposition is shown below. 2HCl(g) → H2(g) + Cl2(g) Hydrogen chloride was added to a container which already contained some hydrogen. After the hydrogen chloride has decomposed for some time, the final volumes of hydrogen chloride, hydrogen and chlorine in the container were determined. The volumes, measured in cm3 at room conditions, before and after the reaction are shown in the table. HCl H2 Cl2 before 200 20 0 after x 100 80 What is the value x? A 0 B 20 C 40 D 160

4 6092/Chemistry/2024 Term 1 Weighted Assessment 4 A solution containing one mole of sodium hydroxide is added to a solution containing one mole of iron(III) sulfate. The equation is shown below: Fe2(SO4)3(aq) + 6NaOH(aq) → 2Fe(OH)3(s) + 3Na2SO4(aq) What is the number of moles of iron(III) hydroxide precipitated? A 3 1 B 2 1 C 6 1 D 3 5 In two experiments to study the rate of reaction between dilute hydrochloric acid and excess zinc powder, the total volume of hydrogen formed was measured at regular time intervals and graphs were plotted from the results. What can be deduced from the graphs? 1 The acid in experiment I was more concentrated than in experiment II. 2 After time t, the reaction in experiment II was still proceeding. 3 The rate of evolution of hydrogen was the same in both experiments at time t. A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 Question 1 2 3 4 5 Answer total volume of hydrogen / cm3 time /s graph for experiment I graph for experiment II t 0

5 6092/Chemistry/2024 Term 1 Weighted Assessment

5 6092/Chemistry/2024 Term 1 Weighted Assessment For Examiner’s Use Section B Answer all questions. Write your answers in the spaces provided. 6 A student was given a sample of a metal hydroxide of formula, B(OH)2. The student was asked to identify the element B by titrating an aqueous solution of B(OH)2 with 0.095 mol/dm3 nitric acid. A sample of B(OH)2 was placed in a weighed container, which was reweighed. mass of container + B(OH)2 = 10.94 g mass of container = 8.89 g The sample of B(OH)2 was transferred to a flask and made up to 250 cm3 with water. This was solution S. 25.0 cm3 of S was transferred to a conical flask. A few drops of methyl orange indic