Chapter 8.4, Problem 27PP

(a)

Interpretation Introduction

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

  $\text{Zn}\left(\text{s}\right){\text{ + Cl}}_{\text{2}}\left(\text{g}\right)\to {\text{ZnCl}}_{\text{2}}\left(\text{s}\right)$

Concept Introduction:

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.

If the oxidation number of an element increases then it undergoes oxidation and if the oxidation number of the element decreases then it undergoes reduction.

(b)

Interpretation Introduction

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

  ${\text{Cl}}_{\text{2}}\left(\text{g}\right)\text{ + 2NaBr}\left(\text{aq}\right)\to \text{2NaCl}\left(\text{aq}\right){\text{ + Br}}_{\text{2}}\left(\text{l}\right)$

Concept Introduction:

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.

If the oxidation number of an element increases then it undergoes oxidation and if the oxidation number of the element decreases then it undergoes reduction.

(c)

Interpretation Introduction

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

  $\text{2PbO}\left(\text{s}\right)\to \text{2Pb}\left(\text{s}\right){\text{ + O}}_{\text{2}}\left(\text{g}\right)$

Concept Introduction:

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.

If the oxidation number of an element increases then it undergoes oxidation and if the oxidation number of the element decreases then it undergoes reduction.

(d)

Interpretation Introduction

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

  ${\text{2Fe}}^{\text{3+}}\left(\text{aq}\right){\text{ + Sn}}^{\text{2+}}\left(\text{aq}\right)\to {\text{2Fe}}^{\text{2+}}\left(\text{aq}\right){\text{ + Sn}}^{\text{4+}}\left(\text{aq}\right)$

Concept Introduction:

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.

If the oxidation number of an element increases then it undergoes oxidation and if the oxidation number of the element decreases then it undergoes reduction.