Chapter 17.2, Problem 14SP

Interpretation Introduction

Interpretation: The amount of heat produced during the chemical reaction is to be found.

Concept introduction: Limiting Reactant is the reactant in a chemical reaction that limits the amount of product that can be produced. Excess Reactant is the reactant in a chemical reaction that remains even after the reaction is complete and when the limiting reactant is completely consumed.

Answer to Problem 14SP

The kilojoules of heat produced when $3.40\text{ mol}$ of ${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}$ reacts with an excess of $\text{CO}$ is $89.4\text{ kJ}$

Explanation of Solution

The given chemical reaction is

  ${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}\text{(s)+3CO(g)}\to {\text{2Fe(s)+3CO}}_{\text{2}}\text{(g)+26}\text{.3 kJ}$

The heat has been released which means the reaction is exothermic. Also, it is given that $\text{CO}$ is in excess, thus ${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}$ is the limiting reactant and will decide the amount of formed and heat released.

It can be seen from the chemical reaction given that when $1\text{ mol}$ of ${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}$ reacts, the energy released is = $\text{26}\text{.3 kJ}$

Thus, when $3.40\text{ mol}$ of ${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}$ reacts, the energy released is = $\frac{\text{26}\text{.3 kJ}}{\text{1}\text{.0 mol}}\times 3.40\text{ mol}=89.4\text{ kJ}$