Chapter 18, Problem 111E

Interpretation Introduction

Interpretation: The minimum amount of hydrogen gas in grams is to be calculated.

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 mass of the second reactant from the given mass of first reactant, follow the following solution map:

$\boxed{\begin{array}{l}\text{given}\\ \text{mass}\text{of}\text{first}\\ \text{reactant}\end{array}}\underset{\begin{array}{l}\text{using}\\ \text{molar}\\ \text{mass}\\ \text{as}\text{a}\\ \text{conversion}\\ \text{factor}\end{array}}{\to }\boxed{\begin{array}{l}\text{moles of}\\ \text{ first}\\ \text{reactant}\end{array}}\underset{\begin{array}{l}\text{By}\\ \text{using}\\ \text{conversion}\\ \text{factor}\end{array}}{\to }\boxed{\begin{array}{l}\text{moles}\text{of}\\ \text{ second}\\ \text{reactant}\end{array}}\underset{\begin{array}{l}\text{using}\\ \text{molar}\\ \text{mass}\\ \text{as}\text{a}\\ \text{conversion}\\ \text{factor}\end{array}}{\to }\boxed{\begin{array}{l}\text{mass}\text{of}\\ \text{ second}\\ \text{reactant}\end{array}}$

The conversion factor used to convert the moles of first reactant into the moles of second reactant is basically the stoichiometric relationship between moles of reactant and moles of product. The conversion factor is obtained from the balanced chemical equation. The mass of the second reactant is converted into their corresponding moles by the use of their corresponding molar masses.