Exercise TEST 1 - chm256 PDF

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QUESTION 1a) A 250 mL of solution containing 0 g of magnesium chloride dihydrate,MgCl 2 .2H 2 O was prepared. Find the concentration of the solution in:i. parts per million (ppm)ii. molarityiii. % (w/v)(5 marks)b) Explain the preparation of 250 mL solution of 25 ppm Na+, from solid sodiumsulfate (Na...

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QUESTION 1

a) A 250 mL of solution containing 0.5259 g of magnesium chloride dihydrate, MgCl2.2H2O was prepared. Find the concentration of the solution in:

i. parts per million (ppm) ii. molarity iii. % (w/v) (5 marks)

b) Explain the preparation of 250 mL solution of 25 ppm Na+, from solid sodium sulfate (Na2SO4). (5 marks) c) State the objective of quantitative analysis and give one (1) example study of this type of analysis. (2 marks)

QUESTION 2 a) Distinguish between accuracy and precision in terms of meaning and formula. (4 marks) b) Identify three (3) examples from determinate error that might occur during titration process. (3 marks)

QUESTION 3 The percentage of iron recorded from an analysis of steel sample are shown in the following table: Sample No Percentage of iron (%) a)

1

2

3

4

5

42.24

42.19

42.26

42.09

42.15

Determine the mean and median from the set of data result. (3 marks)

b)

Using a Q test, evaluate whether the possible outlier in the data should be retained or rejected at 95% confidence level. (4 marks)

c)

Calculate the confidence limit of the data set that can be reported at 95% confidence interval. (5 marks)

QUESTION 4 a)

Describe the technique to calibrate 250 mL volumetric flask. (4 marks)

b)

List two (2) techniques that do not require acids for cleaning glassware. (2 marks)

c)

State function of the oven, furnace and hotplate. (3 marks)

END OF QUESTIONS

APPENDIX 1

APPENDIX 2...