2025 GDLSS P2

1 GREENDALE SECONDARY SCHOOL Preliminary Examination 2025 STUDENT NAME CLASS 4 TEACHING GROUP REG. NO CHEMISTRY Paper 2 Candidates answer on the Question Paper. No Additional Materials are required. 6092/02 1 hour 45 minutes READ THESE INSTRUCTIONS FIRST Write your name, class, teaching group and register number in the spaces provided above. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 24. The use of an approved scientific calculator is expected, where appropriate. This document consists of 24 printed pages. [Turn over

2 Section A Answer all questions. 1 Choose from the elements listed to answer the questions. hydrogen nitrogen neon magnesium sulfur potassium bromine Each element may be used once, more than once or not at all. Identify the following elements. (a) These elements form basic oxides. ……..…………………………………………………………………………………... [1] (b) Atoms of this element gain two electrons when they form ions. ……..…………………………………………………………………………………... [1] (c) These two elements combine together to form a covalent compound with a formula of the type XY3. ……..…………………………………………………………………………………... [1] (d) This element has a melting point below room temperature but a boiling point above room temperature. ……..…………………………………………………………………………………... [1] (e) This element has a proton number of 19. ……..…………………………………………………………………………………... [1] [Total: 5]

3 2 Tritium is an isotope of hydrogen. Fig. 2.1 shows the structure of an ion of tritium. Fig. 2.1 (a) State the proton number and mass number of the ion shown in Fig. 2.1. proton number …………………… mass number …………………… [2] (b) Using the symbol T to represent tritium, give the formulae of (i) the ion shown in Fig. 2.1, ...………..……… [1] (ii) the compound formed between tritium and calcium. ...………..……… [1] (c) Predict whether the oxide of tritium is a solid, a liquid or a gas at room temperature and pressure. Explain your reasoning. ...…………………………………………………………………………………………... ……..…………………………………………………………………………………... [1] [Total: 5]

4 3 Fig. 3.1 shows some information about the Haber process for making ammonia. Fig. 3.1 (a) Explain, with the help of an equation, why the nitrogen and hydrogen are mixed in a ratio of 1:3 by volume. ……..…………………………………………………………………………………....... ……..…………………………………………………………………………………....... ……..…………………………………………………………………………………....... ……..…………………………………………………………………………………... [2] (b) (i) Name the catalyst used in the process. …………………………………………………………………………………... [1] (ii) Explain why the catalyst is finely divided. .…………………………………………………………………………………....... …………………………………………………………………………………... [1] (c) When the mixture of hydrogen, nitrogen and ammonia enters the cooler, the ammonia turns to a liquid but the other gases do not. What does this tell you about the boiling point of ammonia? ……..…………………………………………………………………………………... [1] [Total: 5]

5 4 Two naturally occurring ores of copper are cuprite, Cu2O, and tenorite, CuO. (a) State the oxidation state of copper in each ore. oxidation state of copper in Cu2O ………………….. oxidation state of copper in CuO ………………….. [1] (b) A sample of one of the ores was analysed and found to contain 4.48 g copper and 1.12 g oxygen. Calculate the empirical formula for the copper oxide in the ore, and deduce the name of the ore. name of ore …………………. [2] (c) Copper metal can be extracted by heating ores of copper with carbon. Copper metal is commonly used as a catalyst for the reaction between zinc and dilute acid. Describe experiments to show that copper metal acts as a catalyst in the reaction of zinc and dilute acid. Predict the results of the experiments. ……..…………………………………………………………………………………....... ……..…………………………………………………………………………………....... ……..…………………………………………………………………………………....... ……..…………………………………………………………………………………....... ……..…………………………………………………………………………………... [2] [Total: 5]

6 5 An experiment was carried out to measure the rate of reaction between excess powdered calcium carbonate and dilute acids. (a) In Experiment 1, 25 cm3 of 1.5 mol/dm3 hydrochloric acid was used. A further experiment using hydrochloric acid, Experiment 2, was carried out. Fig. 5.1 shows the results of Experiments 1 and 2. The total volume of carbon dioxide produced in Experiment 2 is half of Experiment 1. Fig. 5.1 Suggest the concentration and volume of acid used for Experiment 2. concentration ………………….…. mol/dm3 volume …………………..… cm3 [2] volume of carbon dioxide/ cm3 Experiment 1 Experiment 2 time/ s

7 (b) Experiment 3 was carried out using 25 cm3 of 1.5 mol/dm3 sulfuric acid. The initial rate of reaction for Experiment 3 was higher than for the other experiments but the reaction stopped suddenly after only a small volume of gas had been given off. (i) Explain why the initial rate of reaction was higher than for the other experiments. Use ideas about particles in your answer. ………………………………………………………………………………........... ………………………………………………………………………………………. ………………………………………………………………………………........... ………………………………………………………………………………........... ………………………………………………………………………………………. ..…………………………………………………………………………………. [2] (ii) Explain why the reaction stops suddenly. ………………………………………………………………………………………. ..…………………………………………………………………………………. [1] [Total: 5]

8 6 Table 6.1 shows some information about the homologous series of a class of organic compounds called acyl chlorides. Table 6.1 name condensed formula displayed formula ethanoyl chloride CH3COCl butanoyl chloride C3H7COCl (a) (i) Complete Table 6.1 to show the name, condensed formula and displayed formula of the acyl chloride that occurs between ethanoyl chloride and butanoyl chloride in the homologous series. [2] (ii) Explain how you can tell that these molecules are from the same homologous series. ………………………………………………………………………………........... ………………………………………………………………………………………. ..…………………………………………………………………………………. [2] (iii) Predict the condensed formula for the acyl chloride that contains 9 carbon atoms. ..…………………………………………………………………………………. [1]

9 (b) Butanoyl chloride reacts with methanol in the following reaction. C3H7COCl + CH3OH → C3H7COOCH3 + HCl compound X (i) Name compound X. ..…………………………………………………………………………………. [1] (ii) Butanoic acid also reacts with methanol. Write an equation for the reaction of butanoic acid with methanol. [1] (iii) Give one similarity and one difference between the reaction of butanoyl chloride with methanol and the reaction of butanoic acid with methanol. similarity ……………………………………………………………………........... ………………………………………………………………………………………. difference ..…………………………………………………………………........... ..…………………………………………………………………………………. [2] [Total: 9]

10 7 Ethanol, C2H5OH, can be manufactured from either ethene or glucose. (a) Write an equation for the production of ethanol from ethene and state the conditions under which the reaction tak