Edexcel Jun 2012 Paper 6 Q1

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Answer ALL the questions. Write your answers in the spaces provided. (a) The colours of aqueous solutions containing chromium(III) chloride and nickel(II) chloride are similar. What colour are these solutions? (1)(b) Tests were carried out on a dilute aqueous solution of chromium(III) chloride. Complete the table below. You may use either names or formulae unless only one of these is specified. (i) (ii) Test Add a few drops of dilute sodium hydroxide solution to the chromium(III) chloride solution. Add dilute sodium hydroxide to the mixture made in (i), until the sodium hydroxide is present in excess. (iii) Add a few drops of dilute ammonia to another sample of the chromium(III) chloride solution. Observations A precipitate forms. Inferences The precipitate isThe complex ion [Cr(OH)6]3 forms. (1) (1)The substance containing chromium which is observed on adding the ammonia is(2) *P39311A0216*<br /> Observations A solution forms. A yellow solution forms. (iv) Test Continue to add dilute ammonia to the mixture in (iii) until the ammonia is present in excess. (v) Warm another sample of the chromium(III) chloride solution with alkaline hydrogen peroxide solution, which acts as an oxidizing agent. Inferences The formula of the chromium containing ion in the solution isThe formula of the ion causing the yellow colour is(1) (1) Add sulfuric acid to the resulting mixture. The solution goes orange when sulfuric acid is added. The ion causing the orange colour is dichromate(VI), Cr2O7 2. (c) Tests (i) and (ii) above were repeated on an aqueous solution of nickel(II) chloride. In what way, other than any difference in colour, does the reaction of dilute sodium hydroxide solution with nickel(II) chloride differ from its reactions with chromium(III) chloride? (1)(Total for Question 1 = 8 marks) *P39311A0316* Turn over<br />

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