Question

Give a chemical test to distinguish between :

(a) dilute sulphuric acid and dilute hydrochloric acid,

(b) dilute sulphuric acid and conc. sulphuric acid.

Answer 1

(a) Bring a glass rod dipped in Ammonia solution near the mouth of each test tubes
containing dil. HCl and dil. $H_{2}S{O}_4$ each

Dil. HCl	Dil.$H_{2}S{O}_4$
White fumes of ammonium chloride	No such fumes

(b)
1. Dilute sulphuric acid treated with zinc gives Hydrogen gas which bums with pop
sound. Concentrated $H_{2}S{O}_4$ gives $S{O}_2$ gas with zinc and the gas turns Acidified
potassium dichromate paper green.
2. Barium chloride solution gives white ppt. with dilute $H_{2}S{O}_4$, This white ppt. is
insoluble in all acids.
Concentrated $H_{2}S{O}_4$ and NaCl mixture when heated gives dense white fumes if
glass rod dipped in Ammonia solution is brought near it.