Chapter 15.1, Problem 3PP

(a)

Interpretation Introduction

Interpretation: In the following reaction, identify the reactant that is oxidized and the reactant that is reduced:

  $\text{4Al}\left(\text{s}\right){\text{ + 3O}}_{\text{2}}\left(\text{g}\right)\to {\text{2Al}}_{\text{2}}{\text{O}}_{\text{3}}\left(\text{s}\right)$

Concept Introduction: In an oxidation reaction the oxidation number of the element increase or becomes more positive. In a reduction reaction the oxidation number of the element decrease or becomes more negative.

The rules for assigning oxidation number to elements are:

• For an element in its free state it is assigned an oxidation number of zero.
• Monatomic ions have oxidation number that is equal to charge of the monatomic ion.
• Alkali metals have +1 oxidation number, alkaline earth metals have +2 oxidation number and halogens are assigned -1 oxidation number.
• In most compounds H is assigned a +1 oxidation number and O is assigned a -2 oxidation number.
• For a neutral compound the summation of oxidation numbers of all elements in the compound is zero.

(b)

Interpretation Introduction

Interpretation: In the following reaction, identify the reactant that is oxidized and the reactant that is reduced:

  $\text{Zn}\left(\text{s}\right){\text{ + 2H}}^{\text{+}}\left(\text{aq}\right)\to {\text{Zn}}^{\text{2+}}{\text{+ H}}_{\text{2}}\left(\text{g}\right)$

Concept Introduction: In an oxidation reaction the oxidation number of the element increase or becomes more positive. In a reduction reaction the oxidation number of the element decrease or becomes more negative.

The rules for assigning oxidation number to elements are:

• For an element in its free state it is assigned an oxidation number of zero.
• Monatomic ions have oxidation number that is equal to charge of the monatomic ion.
• Alkali metals have +1 oxidation number, alkaline earth metals have +2 oxidation number and halogens are assigned -1 oxidation number.
• In most compounds H is assigned a +1 oxidation number and O is assigned a -2 oxidation number.
• For a neutral compound the summation of oxidation numbers of all elements in the compound is zero.

(c)

Interpretation Introduction

Interpretation: In the following reaction, identify the reactant that is oxidized and the reactant that is reduced:

  ${\text{F}}_{\text{2}}\left(\text{g}\right){\text{ + 2Br}}^{\text{-}}\left(\text{aq}\right)\to {\text{2F}}^{\text{-}}\left(\text{aq}\right){\text{ + Br}}_{\text{2}}\left(\text{l}\right)$

Concept Introduction: In an oxidation reaction the oxidation number of the element increase or becomes more positive. In a reduction reaction the oxidation number of the element decrease or becomes more negative.

The rules for assigning oxidation number to elements are:

• For an element in its free state it is assigned an oxidation number of zero.
• Monatomic ions have oxidation number that is equal to charge of the monatomic ion.
• Alkali metals have +1 oxidation number, alkaline earth metals have +2 oxidation number and halogens are assigned -1 oxidation number.
• In most compounds H is assigned a +1 oxidation number and O is assigned a -2 oxidation number.
• For a neutral compound the summation of oxidation numbers of all elements in the compound is zero.