Chapter 9, Problem 25A

Interpretation Introduction

Interpretation:

The amount of iodine gas formed when $4.50\times {10}^3\text{g}$ of chlorine gas is bubbled through excess potassium iodide needs to be deduced based on the given reaction.

Concept Introduction:

• A chemical reaction is expressed as a chemical equation having reactants and products on the left and right side of the reaction arrow respectively.

  $\text{Reactants }\to \text{ Products}$

• The coefficient of a balanced chemical equation, i.e., the stoichiometry gives the amount of reactants and products involved in the reaction.
• Chemical equations can therefore be used to determine the amount of products formed from a known quantity of reactants.

Answer to Problem 25A

Mass of I₂= $1.62\times {10}^4\text{g}$

Explanation of Solution

The given reaction is:

  ${\text{Cl}}_{\text{2}}\text{(g) + KI(aq)}\to {\text{I}}_2\text{(s) + KCl(aq)}$

The balanced equation is:

  ${\text{Cl}}_{\text{2}}\text{(g) + 2KI(aq)}\to {\text{I}}_2\text{(s) + 2KCl(aq)}$

Step 1: Calculate the moles of Cl₂present:

Mass of Cl₂ present = $4.50\times {10}^3\text{g}$

Molar mass of Cl₂ = 71 g/mol

  $\begin{array}{c}{\text{Moles of Cl}}_2\text{ = }\frac{{\text{Mass of Cl}}_2}{{\text{Molar Mass Cl}}_2}\end{array}$

         $\begin{array}{c}=\frac{\text{4}\text{.50}\times {\text{10}}^3\text{ g}}{71\text{ g/mol}}\end{array}$

         $\begin{array}{c}=63.38\text{ moles}\end{array}$

Step 2: Calculate the moles of I₂ formed:

Based on the reaction stoichiometry:

1 mole of Cl₂ forms 1 mole of I_2.

Therefore, 63.38 moles of Cl₂will yield 63.38 moles of I_2.

Step 3: Calculate the mass of I₂ formed:

Moles of I₂ formed= 63.38 mol

Molecular weight of I2 = 253.8 g/mol

  $\begin{array}{c}{\text{Mass of I}}_2\text{ = Moles }\times \text{ Molecular weight}\end{array}$

        $\begin{array}{c}=63.38\text{ moles }\times \text{ 253}\text{.8 g/mol}\end{array}$

       $\begin{array}{c}\text{ = 1}\text{.62}\times {\text{10}}^4\text{ g}\end{array}$

Conclusion

Therefore, the mass of I₂ formed is around $1.62\times {10}^4\text{ g}$ .