Question

The black compound formed during the reaction between sodium thiosulphate and silver nitrate is

• A. silver thiosulphate
• B. silver sulphide
• C. silver sulphate
• D. silver sulphite

Answer 1

Answer: (B)

With a very dilute solution of $N{a}_2{S}_2,O_3$ silver nitrate gives a white -precipitate which quickly changes colour to yellow, brown and finally black due to the formation of silver sulphide. $2AgN{O}_3+N{a}_2{S}_2{O}_3\to \underset{whiteppt}{A{g}_2{S}_2{O}_3}+NaN{O}_3$ $A{g}_2{S}_2{O}_3+H_{2}O\to \underset{black}{A{g}_{2}S}+H_{2}S{O}_4$