Question

Hydrogen Sulphide ${H_2}S$ gas passes in all the following test tube so that the precipitation observes so which is correct match:
Cu, Sb, Zn, Cd, Pd, Sn, Ni

A.Cd – Black
B.Sb – Orange
C.Ni – Yellow
D.Zn - Brown

Answer 1

Antimony, Sb (III) reacts with ${H_2}S$ gas to form orange precipitate, $S{b_2}{S_3}$ . This sulphide is soluble in solution of hot NaOH which contains excess sulphide ion in hot concentrated HCl.

Complete step by step answer:
When hydrogen sulphide $\left( {{H_2}S} \right)$ gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remains in the solution.
Antimony, Sb (III) reacts with ${H_2}S$ gas to form orange precipitate, $S{b_2}{S_3}$. This sulphide is soluble in solution of hot NaOH which contains excess sulphide ion in hot concentrated HCl.
When ${H_2}S$ gas is passed through the test tube, zinc chloride reacts with ${H_2}S$ gas to form a precipitate of zinc sulphide which is soluble in HCl solution and hence no precipitate is obtained.
When ${H_2}S$ gas is passed through cadmium chloride solution, yellow coloured precipitate of cadmium sulphide (CdS) is formed and aqueous hydrochloric acid (HCl) is also formed.
When ${H_2}S$ gas reacts with Ni, precipitation of solid black nickel sulphide is a mainstay of traditional qualitative inorganic analysis schemes, which begins with the separation of metals on the basis of the solubility of their sulphides.

Therefore, the correct answer is option (B).

Note: Hydrogen sulphide, ${H_2}S$ gas occurs naturally in crude petroleum, natural gas, volcanic gases and hot springs. It can also develop or result from bacterial breakdown of organic matter. It is produced from the human and animal wastes. Hydrogen sulphide is a colourless gas having a strong odour of rotten eggs. Its Boiling point $- 60.2^\circ C$. Shipped as a liquid confined under its own vapour pressure. Its density (liquid) is $8.3\dfrac{{lb}}{{gal}}$ . Its contact with the unconfined liquid can cause frostbite by evaporative cooling. Gas is very toxic by inhalation.