S6 Chemistry Mock Exam (2019-2020) Paper 1B, good revision for our mocks.

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Answer ALL questions. Write your answers in the spaces provided. 1. Methane reacts with chlorine when exposed to sunlight. Chloroform (CHCl3) is one of the products of the reaction. It is an oily li... quid that floats on sodium chloride solution. (a) What would be observed at the beginning of the reaction between methane and chlorine? (1 mark) (b) Draw the electron diagrams, showing electrons in the outermost shell only, for the formation of chloroform from chlorine and methane. (3 marks) 10 cm3 of CH4(g) + 10 cm3 of Cl2(g) saturated NaCl(aq) sunlight 3 Answers written in the margins will not be marked. Answers written in the margins will not be marked. 1. (c) Chloroform vapour undergoes oxidation on standing in air in the presence of light to form highly toxic phosgene gas (COCl2) and hydrogen chloride. Suggest a chemical test to show whether the oxidation of chloroform has occurred. (2 marks) (d) (i) Draw the three-dimensional structure of a phosgene molecule. Use the + and − signs to indicate the partial charges of atoms. (2 marks) (ii) Explain what causes the partial charges of atoms in (d)(i). (2 marks) 4 Answers written in the margins will not be marked. Answers written in the margins will not be marked. 2. 0.98 g of magnesium ribbon was heated strongly in a crucible as shown below. After heating for 30 minutes, some white solids were left. (a) Give ONE reasons why the crucible should be half covered with the lid during heating, as shown in the above diagram. (1 mark) (b) If the empirical formula of the white solid is MgO, calculate the theoretical mass of the white solid left. (2 marks) (c) It was found that the actual mass of the white solid weighed is less than the theoretical mass calculated in (b). Suggest ONE possible source of experimental error. (1 mark) 5 Answers written in the margins will not be marked. Answers written in the margins will not be marked. 3. The diagram below shows the structure of a zinc-carbon cell. (a) The electrolyte is a moist paste of ammonium chloride. Suggest a chemical test to show the presence of ammonium ions in the electrolyte. (2 marks) (b) Mixture Y contains carbon powder and a solid compound. Name the solid compound and give its function in the zinc-carbon cell. (2 marks) (c) Write an overall equation in a zinc-carbon cell involving mixture Y. (1 mark) (d) Comment on the following statement. 'Zinc-carbon cells should be replaced by nickel-metal hydride cells as they c [Show More]

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