You have three unlabelled test-tubes containing ethanol, ethanoic acid and soap solution.

Question

(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 1

(i)

SOLUTION	BLUE LITMUS PAPER	RED LITMUS PAPER	SODIUM METAL
Ethanol	No change	No change	Hydrogen gas
Ethanoic acid	Turns red	No change	Hydrogen gas
Soap	No change	Turns blue	Hydrogen gas

(ii) Hard water contains calcium ions or magnesium ions or both. These ions on reacting with soap solution form insoluble substance called scum.