Chapter 17, Problem 33AE

Interpretation Introduction

Interpretation:

The indicated unbalanced ionic equation has to be balanced in acidic medium.

  ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{OH}+{\text{Cr}}_{\text{2}}{\text{O}}_7^{2-}\to {\text{CH}}_{\text{3}}\text{COOH}+{\text{Cr}}^{3+}$

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 water molecule.
• For the acidic medium, excess electrons are neutralized by addition of ${\text{H}}^{+}$ ions to each side.