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(i) You have three unlabelled test-tubes containing ethanol, ethanoic acid and soap solution. Explain the method you would use to identify the compounds in different test tubes by chemical tests using litmus paper and sodium metal.
(ii) Give the reason of formation of scum when soaps are used with hard water.
Answer
(i)
|
Solution |
Blue litmus paper |
Red litmus paper |
Sodium metal |
|
Ethanol |
No change |
No change |
H 2 gas released |
|
Ethanoic acid |
Red |
No change |
H 2 gas released |
|
Soap |
No change |
Blue |
H 2 gas released |
(ii) Soaps do not work in hard water because they react with calcium and magnesium ions and form a white sticky substance called scum.
