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10 marksQualitative Analysis

CSEC Chemistry · May/June 2005 · Paper 2 · Question 1(b)(iii)

Y is a mixture of two salts. A student carries out tests on a sample of Y, with observations recorded in Table 1. You need to fill in the inferences.

To the first portion of the filtrate from (b) above, add aqueous sodium hydroxide slowly until in excess. Observations: a green precipitate is formed; insoluble in excess aqueous sodium hydroxide. Inferences:

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Other parts of this question

  1. 1(a)(i)In the space below, construct a suitable table and record on it, the temperatures at which the reaction took place with the corresponding times in seconds for…[4 marks]
  2. 1(a)(ii)Using the graph paper provided on page 5, plot a graph of temperature versus time in seconds.[3 marks]
  3. 1(a)(iii)What conclusion can be drawn about the rate of the reaction from the graph?[1 mark]
  4. 1(a)(iv)From the graph, determine the time expected to be taken for the appearance of the sulphur precipitate if the reaction were carried out at 50°C. Indicate on…[2 marks]
  5. 1(a)(v)From the information given on page 3 in the introduction to this question, write a balanced chemical equation for the reaction between aqueous sodium…[2 marks]
  6. 1(b)(i)Heat a small portion of solid Y in a test tube, gently at first and then strongly. Observations: colourless gas evolved with a choking odour; turns acidified…[10 marks]
  7. 1(b)(ii)To the remaining portion of solid Y, add 20 cm³ of distilled water, stir to dissolve and filter. Collect the filtrate and divide into three (3) equal portions.…[10 marks]
  8. 1(b)(iv)To the second portion of the filtrate from (b) above, add aqueous silver nitrate followed by aqueous ammonia. Observations: white precipitate is formed;…[10 marks]
  9. 1(b)(v)To the third portion of the filtrate from (b) above, add aqueous barium nitrate followed by aqueous nitric acid. Observations: a white precipitate is formed;…[10 marks]
  10. 1(c)(i)Hypothesis to be tested[8 marks]
  11. 1(c)(ii)Materials and apparatus[8 marks]
  12. 1(c)(iii)Method[8 marks]
  13. 1(c)(iv)Variables controlled[8 marks]
  14. 1(c)(v)Data to be collected[8 marks]
  15. 1(c)(vi)Results linked to hypothesis[8 marks]

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