Question

To distinguish between ethene and ethyne, we should use:

• A. potassium permanganate solution
• B. bromine water
• C. ammonical cuprous chloride
• D. all of the above

Answer 1

Answer: (C)

ammonical cuprous chloride

The two hydrocarbons can be easily distinguished by simple chemical tests, as ethyne molecule is supposed to have acidic hydrogen.

1. When ethyne is bubbled through ammoniacal silver nitrate solution, a yellow-white precipitate of silver acetylide would be formed.

$C_2{H}_2$ + $2AgN{O}_3$ = $A{g}_2{C}_2$ + $2HN{O}_3$

2. Similarly, ethyne forms a red precipitate of copper acetylide ($C{u}_2{C}_2$) when it is passed through ammoniacal cuprous chloride solution.

Ethene does not react with $AgN{O}_3$ or $C{u}_2{C}_2$ solution.

Hence, the correct option is $\text{C}$