'A' and 'B' are two salts used for washing purposes. Salt 'A' is used for bathing also. Four test tubes I,…
'A' and 'B' are two salts used for washing purposes. Salt 'A' is used for bathing also. Four test tubes I, II, III and IV as mentioned below are taken.
I. Rain water + solution of salt 'A'
II. Rain water + solution of salt 'B'
III. Tubewell water + solution of salt 'A'
IV. Tubewell water + solution of salt 'B'
The test tubes are shaken one by one almost identically for the same time and the lengths of foam formed in each test tube is noted.
(a) In which one of the four test tubes is the foam formed the minimum ?
(b) Differentiate between salt A and salt B.
(c) (i) What are esters ? What happens when an ester reacts with an alkali (say sodium hydroxide) ? Give chemical equation for the reaction.
Solution
(a) (III) /Tubewell water + Solution of Salt A
(b) Salt A: Soap; Na/K salt of long chain carboxylic acids; Does not form lather with hard water.
Salt B: Detergent; sodium salt of sulphonic acids or ammonium salts with chloride or bromide ions; Forms lather even with hard water.
(Any one)
(c) (i) Esters are sweet smelling substances used in making perfumes and flavoring agents. / Formed when alcohol and carboxylic acid react in presence of acid to form ester.
It is converted back to alcohol and a salt of carboxylic acid.
CH3COOC2H5 + NaOH → C2H5OH + CH3COONa