Question

Aqueous solution of ammonium sulphate:
A. Turns blue litmus to red
B. Turns red litmus to blue
C. Bleaches litmus
D. Has no action on litmus

Answer 1

Hint: The solution which is acidic in nature turns blue litmus to red and the solution which is basic in nature turns red litmus to red. Ammonium sulphate is made up of strong acid and weak base and hence it is acidic in nature.

Complete step by step answer:
Ammonium sulphate is an inorganic salt. It has a chemical formula as ${(N{H_4})_2}S{O_4}$ . It is made up of reacting concentrated sulphuric acid with ammonia. The reaction takes place as:
${H_2}S{O_4} + N{H_3} \to {(N{H_4})_2}S{O_4}$
As, sulphuric acid is a very strong acid while ammonia is a beak base. So, ammonium sulphate formed by the combination of strong acid and weak base which make it acidic in nature.
We can also say that on hydrolysis of ammonium sulphate, it generates ${H^ + }$ ions, which shows that it is acidic in nature.
The reaction takes place as:
${(N{H_4})_2}S{O_4} \to 2NH_4^ + + SO_4^{2 - }$
$NH_4^ + + {H_2}O \to N{H_4}OH + {H^ + }$
It is clear that aqueous solution of ammonium sulphate is acidic in nature. It means it will turns blue litmus to red.
Hence, option A is correct.

Note:
Litmus test is used to identify if the solution is acidic or basic. But there is one more way to determine the acidic or basic character of a solution that is by calculating its potential of hydrogen. Represented by $pH$ . At room temperature${25^0}C$ , solutions which have $pH$ less than $7$ are acidic in nature and solutions which have $pH$ greater than $7$ are basic in nature. Solutions which have $pH$ exactly equal to $7$ at room temperature are neutral in nature for example water. The neutral value of the $pH$ depends on the temperature, being lower than $7$ if the temperature increases. The $pH$ value can be less than $0$ for very strong acids, or greater than $14$ for very strong bases.