Chapter 15.1, Problem 15.4QAP

Interpretation Introduction

(a)

Interpretation:

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

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

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.

Interpretation Introduction

(b)

Interpretation:

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

  $\text{Ca}\left(\text{s}\right)\text{ + S}\left(\text{s}\right)\to \text{CaS}\left(\text{s}\right)$

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.

Interpretation Introduction

(c)

Interpretation:

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

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

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.