Chapter 9, Problem 47UTC

The chapter sections lo review are shown in parentheses at the end of each problem
If red spheres represent oxygen atoms, blue spheres represent nitrogen atoms, and all the molecules are gases, (9.2, 9.4)

a. write a balanced equation for the reaction.
b. identify the limiting reactant.

Interpretation Introduction

Interpretation : The balanced chemical equation for the given reaction should be determined.

Concept Introduction : The balance equation for any chemical reaction represents the molecules of reactant and products with same number of atoms at both sides of the equation. The reactant and product molecules must be shown with simplest whole number coefficients.

Answer to Problem 47UTC

  $\text{2 NO}\left(g\right){\text{+ O}}_{\text{2}}\left(g\right)\to {\text{2 NO}}_{\text{2}}\left(g\right)$

Explanation of Solution

Here, in reactant box there are 4 molecules of ${\text{NO}}_{\text{2}}$ and 3 molecules of ${\text{O}}_{\text{2}}$ whereas in product box there are four molecules of ${\text{NO}}_{\text{2}}$ and one molecule of ${\text{O}}_{\text{2}}$ . Hence it should be written as;

  $\begin{array}{l}\text{4 NO}\left(g\right){\text{+ 3 O}}_2\left(g\right)\to {\text{4 NO}}_{\text{2}}\left(g\right){\text{+O}}_2\left(g\right)\\ \text{or 4 NO}\left(g\right){\text{+ 2 O}}_2\left(g\right)\to {\text{4 NO}}_{\text{2}}\left(g\right)\\ \text{or 2 NO}\left(g\right){\text{+ O}}_2\left(g\right)\to {\text{2 NO}}_{\text{2}}\left(g\right)\end{array}$

Interpretation Introduction

Interpretation : The limiting reactant should be determined.

Concept Introduction : Limiting reactant is the reactant for a chemical reaction which is present in limited amount. Since it is present in limited amount therefore it determines the amount of product formed during the chemical reaction.

Answer to Problem 47UTC

NO is limiting reactant for the given reaction.

Explanation of Solution

Here, in reactant box there are 4 molecules of $\text{NO}$ and 3 molecules of ${\text{O}}_{\text{2}}$ whereas in product box there are four molecules of ${\text{NO}}_{\text{2}}$ and one molecule of ${\text{O}}_{\text{2}}$ . It means here ${\text{O}}_{\text{2}}$ is in excess as it is also present in product box and $\text{NO}$ is consumed completely therefore $\text{NO}$ must be limiting reactant here.