Chapter 17, Problem 44AE

(a)

Interpretation Introduction

Interpretation:

The reducing agent has to be identified in indicated unbalanced equation.

  $\mathrm{Mn}{\mathrm{O}}_2+{\text{Br}}^{-}\to {\text{Br}}_2+{\text{Mn}}^{2+}$

Concept Introduction:

In order to balance any redox reaction method used in acidic medium is summarized below.

• In the first step oxidation number of each element is identified.
• The overall reaction is divided into oxidation and reduction held cell based upon changes observed in oxidation states.
• Each side of half-cell equation is balanced except $\text{H}$ and $\text{O}$.  The electrons lost are made equal to electron gained so as to add two half-cells and formulate overall reaction equation.
• In next step, $\text{O}$ atoms are balanced by addition of water molecule.
• For the acidic medium, excess electrons are neutralized by addition of ${\text{H}}^{+}$ ions to each side.

(b)

Interpretation Introduction

Interpretation:

Mass of $\mathrm{Mn}{\mathrm{O}}_2$ required to produce $100.0\text{ mL}$ of $\text{0}{\text{.05 M Mn}}^{2+}$  has to be calculated.

Concept Introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

Volume of ${\text{Br}}_{\text{2}}$ vapor formed at $\text{50 }°\text{C}$ and $\text{1}\text{.4 atm}$ has to be calculated.

Concept Introduction:

Refer to part (a).