The results of testing five samples of water from different areas are shown in the table below. The soap solution was gradually added to 25 cm3 of each sample of water with shaking until a permanent lather (one which lasts for 20 seconds) was obtained.

a. (i) Which samples are permanently hard?

(ii) Which samples are temporarily hard?

(iii) Which sample contains both temporary and permanent hardness?

b. Name a compound which could be present in sample D but not in sample E.

c. Name a compound which could be present in sample E but not in sample D.

d. Explain how the compound you have named in c gets into the water.

e. Sample E was distilled. The water collected was tested with soap solution. What volume of soap solution might you expect to be added to produce a permanent lather? Comment on your answer.

Transcribed Image Text:

Water sample/ 25 cm Volume of soap solution added/cm Before boiling After boiling A 12 1 B 13 6 11 11 D 14 3 E 16 16