Question

Four gases ethane, ethene, ethyne and propene are passed into a wolf bottle containing ammoniacal $AgNO _{3}$ solution. Which gas will come out of wolf bottle?

• A. Only ethyne
• B. Ethane and ethyne
• C. Ethane and ethene
• D. Ethane, ethene and propene

Answer 1

Answer: (D)

Terminal alkynes are precipitated in form of acetylides when they react with $Ag NO _{3}$.
Alkane and alkene do not react with $AgNO _{3}$.
(i) $\underset{\text{ethane}}{C _{2} H _{6}}+ AgNO _{3} \rightarrow$ No reactioin
(ii) $\underset{\text{ethane}}{C _{2} H _{4}}+ AgNO _{3} \rightarrow$ No reactioin
(iii) $\underset{propene}{C _{3} H _{6}}+ AgNO _{3} \rightarrow$ No reactioin
(iv) $\underset{\text { ethyne }}{ HC \equiv CH} + AgNO _{3} \rightarrow A\underset{\text { white ppt. of silver acetylide }}{Ag - C \equiv C -Ag}$
Ethane, ethene and propene do not react with $AgNO _{3}$.
$\therefore $ They come out of wolf bottle.