Chapter 18, Problem 114E

Interpretation Introduction

Interpretation: The minimum volume of hydrogen gas needed for the complete hydrogenation of propyne is to be calculated at STP.

Concept Introduction:

Hydrogenation reaction is the chemical reaction between an unsaturated compound containing either double bonded or triple bonded carbon atoms in the presence of catalyst such as platinum and nickel. The general form of hydrogenation reaction is:

$\begin{array}{l}\text{R}=\text{R}+{\text{H}}_{\text{2}}\stackrel{}{\to }\text{ R}-\text{R}\\ \text{Alkene Hydrogen Alkane }\end{array}$

To determine the volume of hydrogen gas needed for the complete hydrogenation of the given amount of propyne, follow the following solution map:

$\boxed{\begin{array}{l}\text{given}\\ \text{mass}\text{of}\text{propyne}\end{array}}\to \boxed{\text{moles of propyne}}\underset{\begin{array}{l}\text{By}\text{using}\\ \text{conversion}\\ \text{factor}\end{array}}{\to }\boxed{\text{moles}\text{of}{\text{H}}_2}\to \boxed{\text{Volume}\text{of}{\text{H}}_2}$

The mass of propyne is converted into their corresponding moles by the use of their corresponding molar masses. The conversion factor used to convert the moles of propyne into the moles of $H_2$ is basically the stoichiometric relationship between moles of propyne and moles of $H_2$. The conversion factor is obtained from the balanced chemical equation. The moles of $H_2$ is converted into their corresponding volume by the use of molar volume of gas at STP as a conversion factor.