Chapter 4, Problem 4.142P

(a)

Interpretation Introduction

Interpretation:

The oxidized substance and the reduced substance in step 1 and step 2 respectively is to be determined.

Concept introduction:

A redox reaction is a type of reaction that involves the change in oxidation number of a molecule, atom or ion changes due to the transfer of an electron from one species to another.

Oxidation of a species involves the loss of electrons by that species and reduction of a species involves the gain of electrons by that species.

The oxidation number is defined as the formal charge an atom would gain if all the bonds attached to it in a compound are heterolytically cleaved. Oxidation number can be a positive or negative number but cannot be fractional.

(b)

Interpretation Introduction

Interpretation:

The mass of ${\text{O}}_2$ that is dissolved in $50.00\text{mL}$ of water sample is to be determined.

Concept introduction:

Stoichiometry of a reaction is utilized to determine the amount of any species in the reaction by the relationship between the reactants and products.

Consider the general reaction,

$\text{A}+2\text{B}\to 3\text{C}$

One mole of $\text{A}$ reacts with two moles of $\text{B}$ to produce three moles of $\text{C}$. The stoichiometric ratio between A and B is 1:2, the stoichiometric ratio between A and C is 1:3 and the stoichiometric ratio between B and C is 2:3.