The flow chart below shows the various stages of water treatment. Study it and answer the questions that follow.

The flow chart below shows the various stages of water treatment. Study it and answer the questions that follow.

i) What is the purpose of filtration unit I
ii) What is the name of process X
What is the purpose of
I.Process X
II.Addition of sodium hypochlorite
b) A sample of tap water was found to contain magnesium sulphate.
i) What type of hardness was present in the water?
ii) Explain how the hardness can be removed.
c)i) Describe how a solid sample of calcium carbonate can be prepared starting with magnesium oxide.
ii) State one use of calcium carbonate.

Answers

(a) (i) To remove the large solid particles from water
(ii) Sedimentation
(iii) I. Cause the small suspended particles to settle down.
II. To kill germs/microorganisms/microbes
(b) (i) Permanent
(ii) Addition of Na₂CO₃ which precipitates
Mg²⁺ as MgCO₃
OR
Use of ion exchange resin which will remove Mg2+ or distillation where MgSO4 is left behind as residue.
(c) (i) Add excess calcium oxide to dilute HCl/HNO₃ filter to obtain the filtrate and add aqueous Na₂CO₃/K₂CO₃ to the filtrate to precipitate CaCO₃; wash the precipitate with distilled water and dry it between filter
papers
(ii) Used as chalk
- Used in the extraction of iron.

sharon kalunda answered the question on March 19, 2019 at 14:02

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