Page 470 - SUBSEC October 2017_Neat

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Answer ALL questions.

1. You are provided with Sample A, which is a mixture of fine sand and CuSO . nH O crystals in a
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crucible. You are required to determine the value of n by following the procedure outlined below and
recording your data in Table 1.

(a) Procedure DO NOT WRITE IN THIS AREA

A. Weigh the crucible and Sample A (M1).

B. Heat the sample over a bunsen burner for approximately 15 minutes.
Record any changes in appearance of the sample.

C. Remove the sample from the heat, cool in a dessicator for five minutes and reweigh
the crucible and sample (M2).

D. Remove the sample as completely as possible in 250 cm of water.
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Record your observation.

E. Filter the mixture from Step D above through Whatman #4 filter paper.
Wash and dry the crucible.

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F. Wash the residue in the filter paper with two separate 100 cm aliquots of water.
Record the colour of the filtrate from each of these washings. DO NOT WRITE IN THIS AREA

G. Transfer the washed residue to the previously dried crucible.

H. Dry the transferred residue over a bunsen flame. Record your observations.

I. Cool the dried residue in a dessicator for five minutes.

J. Weigh the dried cool residue in the crucible (M3).

(b) Outline the procedure that would have been followed to obtain the results in (a).

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[5 marks]

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