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2 marksMixtures and Separations

CSEC Chemistry · May/June 2013 · Paper 2 · Question 1(c)(iii)

You are provided with a mixture of solid sodium sulfate and sodium chloride. Plan and design an experiment to obtain either solid sodium sulfate or solid sodium chloride from the mixture.

List the MAIN observations that will be expected at EACH stage of the experiment.

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  1. 1(a)(i)For EACH temperature in Table 1, calculate the mass of potassium iodide that was dissolved in the beaker of water, and record the value in the space provided.[2 marks]
  2. 1(a)(ii)On Figure 1, plot mass of salt dissolved (solubility) against temperature, and draw a straight line through the points.[3 marks]
  3. 1(a)(iii)From the graph, determine the solubility (in grams per 100 cm³) of potassium iodide at 70 °C.[1 mark]
  4. 1(a)(iv)100 cm³ of distilled water is saturated with potassium iodide at 70 °C. Calculate the mass of potassium iodide that will be precipitated out from solution, if…[2 marks]
  5. 1(a)(v)Calculate the concentration (mol dm⁻³) of a saturated solution of potassium iodide at 30 °C. (RAM: K = 39, I = 127).[3 marks]
  6. 1(b)Explain why the statement above is true.[4 marks]
  7. 1(c)(i)A suggested list of apparatus and chemicals which you will use in obtaining the pure solid sample of EITHER of the two salts.[1 mark]
  8. 1(c)(ii)An outline of the steps for the procedure to be used.[3 marks]
  9. 1(d)Complete the table by inserting the appropriate inferences.[4 marks]

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