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3 marksQualitative Analysis

CSEC Chemistry · May/June 2014 · Paper 2 · Question 1(c)(ii)

Students are testing for the presence of sulfite ions in an unknown substance. Figure 3 shows the apparatus used, where dilute acid and the unknown substance (containing sulfite) are in Flask 1, and the gas produced passes into Flask 2 containing Solution Y.

With reference to Solution Y identified in (i) above, explain the changes that would be observed in Flask 2 if the unknown substance contained the sulfite ion. Expected changes: Explanation:

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Other parts of this question

  1. 1(a)(i)Use the data from Table 1 to plot a graph of temperature against volume of acid using the axes provided in Figure 1 on page 3. Two of the points have been…[4 marks]
  2. 1(a)(ii)From the graph in (a)(i), determine the volume of acid required to neutralize 25 cm³ of potassium hydroxide.[1 mark]
  3. 1(a)(iii)Determine the temperature difference during the reaction.[1 mark]
  4. 1(a)(iv)Calculate the heat change at the point of neutralization for the reaction between potassium hydroxide and hydrochloric acid. [The specific heat capacity of…[3 marks]
  5. 1(b)(i)Suggest a suitable aim for this experiment.[2 marks]
  6. 1(b)(ii)Describe what will happen to the contents of Beaker A after 30 seconds.[2 marks]
  7. 1(b)(iii)Write a suitable ionic equation for the reaction occurring in Beaker A.[2 marks]
  8. 1(b)(iv)How would the contents of Beaker B differ from the contents of Beaker A after each is left for 30 seconds?[2 marks]
  9. 1(b)(v)Explain your answer in (iv) above.[3 marks]
  10. 1(c)(i)Identify Solution Y.[1 mark]
  11. 1(c)(iii)How would you modify the experiment to confirm the presence of carbonate instead of the sulfite ion?[1 mark]

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