Chapter 18.2, Problem 5RQ

(a)

Interpretation Introduction

Interpretation: Reduction reaction of ${\text{Ag}}^{\text{+}}\left(\text{aq}\right)$ to $\text{Ag}\left(\text{s}\right)$ needs to be balanced.

Concept Introduction: In oxidation-reduction reaction, transfer of electron/s takes place. The transfer of electron, results in the formation of ions. In oxidation, loss of electron/s takes place and in reduction, gain of electron/s takes place.

Answer to Problem 5RQ

Balanced reaction of ${\text{Ag}}^{\text{+}}\left(\text{aq}\right)$ to $\text{Ag}\left(\text{s}\right)$ is-

${\text{Ag}}^{\text{+}}\left(\text{aq}\right)\to \text{Ag}\left(\text{s}\right)+{\text{e}}^{-}$

Explanation of Solution

Reduction half reaction of ${\text{Ag}}^{\text{+}}\left(\text{aq}\right)$ to $\text{Ag}\left(\text{s}\right)$ is as follows:

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

Number of Ag in both sides is equal. The charge on the left is +1 and on the right side is $0$ . Overall charge becomes zero, if ${\text{1e}}^{-}$ is added on the right. Hence, the balanced reaction is-

${\text{Ag}}^{\text{+}}\left(\text{aq}\right)\to \text{Ag}\left(\text{s}\right)+{\text{e}}^{-}$

(b)

Interpretation Introduction

Interpretation: Oxidation reaction of $\text{Cu}\left(\text{s}\right)$ to ${\text{Cu}}^{\text{2+}}\left(\text{s}\right)$ needs to be balanced.

Concept Introduction: In oxidation-reduction reaction, transfer of electron/s takes place. The transfer of electron, results in the formation of ions. In oxidation, loss of electron/s takes place and in reduction, gain of electron/s takes place.

Answer to Problem 5RQ

Balanced reaction of $\text{Cu}\left(\text{s}\right)$ to ${\text{Cu}}^{\text{2+}}\left(\text{s}\right)$ is as follows:

$\text{Cu}\left(\text{s}\right)\to {\text{Cu}}^{\text{2+}}\left(\text{aq}\right)+2{\text{e}}^{-}$

Explanation of Solution

Oxidation half-reaction $\text{Cu}\left(\text{s}\right)$ to ${\text{Cu}}^{\text{2+}}\left(\text{s}\right)$ is as follows:

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

Number of Cu in both sides is balanced. The charge on the left is zero and on the right side is $2+$ . Overall charge becomes zero if $2{\text{e}}^{-}$ are added on the right. Hence, balanced reaction is as follows:

$\text{Cu}\left(\text{s}\right)\to {\text{Cu}}^{\text{2+}}\left(\text{aq}\right)+2{\text{e}}^{-}$