Hard Water

Question 1

(6) When mixed with a small volume of soap solution, hard water does not form a
lather.
You are provided with three unlabelled samples of water.
t one is soft water
t one is permanent hard water
t one is temporary hard water
You are provided with soap solution and the usual laboratory apparatus.
Describe tests that you should carry out on each sample to identify the type of
water in each sample.

Answer 1

soft
 add soap (solution)
 shake/ mix
 lather (immediately)
 no scum/ no precipitate

permanent hard
 add soap (solution)
 shake
 no lather / less than with 
soft water
 scum/ precipitate
 boiled sample
 same results / boiling does not change
 becomes soft after ion exchange but not after boiling

temporary hard
 add soap (solution)
 shake
 no lather / less than with soft water
 scum/ precipitate
 boiled sample
 after boiling precipitate / (lime)scale formed
 lather (immediately)