Question

Question:Which of the following statement(s) is/are true?

a. Copper metal can be oxidized by Ag (at standardconditions).

b. In a galvanic cell the oxidizing agent in the cell reactionis present at the anode.

c. In a cell using the half-reactions ${\mathbf{Al}}^{\mathbf{3}\mathbf{+}}\mathbf{+}\mathbf{3}{\mathbf{e}}^{\mathbf{-}}\stackrel{}{\mathbf{\to }}\mathbf{}\mathbf{Al}$and ${\mathbf{Mg}}^{\mathbf{2}\mathbf{+}}\mathbf{+}\mathbf{2}{\mathbf{e}}^{\mathbf{-}}\stackrel{}{\mathbf{\to }}\mathbf{}\mathbf{Mg}$, aluminum functions as the anode.

d. In a concentration cell, electrons always flow fromthe compartment with the lower ion concentrationto the compartment with the higher ion concentration.

e. In a galvanic cell the negative ions in the salt bridgeflow in the same direction as the electrons.

Short answer

1. True
2. False
3. False
4. True
5. false

Step-by-step solution

verifying whether (a) is true or not

Half equations can be written as,

$$\begin{gathered} {\mathrm{Ag}}^{+}+{\mathrm{e}}^{-}\stackrel{}{\to }\mathrm{Ag}\left({\mathrm{E}}^0=0.8\mathrm{V}\right) \\ {\mathrm{Cu}}^{+2}+2{\mathrm{e}}^{-}\stackrel{}{\to }\mathrm{Cu}\left({\mathrm{E}}^0=0.34\mathrm{V}\right) \\ {\mathrm{E}}_{\mathrm{cell}}^{\circ }={\mathrm{E}}_{\mathrm{cathode}}^{\circ }-{\mathrm{E}}_{\mathrm{anode}}^{\circ } \\ {\mathrm{E}}_{\mathrm{cell}}^{\circ }=0.8\mathrm{V}-0.34\mathrm{V} \\ {\mathrm{E}}_{\mathrm{cell}}^{\circ }=0.46\mathrm{V} \end{gathered}$$

$E_{cell}^{\circ }$is positive.

Hence,Copper metal can be oxidized by Ag⁺, the statement is true.

verifying whether (b) is true or not

In a galvanic cell, the oxidizing agent carries on the reduction. Reduction occurs at the cathode. Hence the statement is not true.

verifying whether (c) is true or not

$$\begin{gathered} {\mathrm{Al}}^{+3}+3{\mathrm{e}}^{-}\stackrel{}{\to }\mathrm{Al}\left({\mathrm{E}}^0=-1.66\mathrm{V}\right) \\ {\mathrm{Mg}}^{+2}+2{\mathrm{e}}^{-}\stackrel{}{\to }\mathrm{Mg}\left({\mathrm{E}}^0=-2.37\mathrm{V}\right) \\ {\mathrm{E}}_{\mathrm{cell}}^{\circ }={\mathrm{E}}_{\mathrm{cathode}}^{\circ }-{\mathrm{E}}_{\mathrm{anode}}^{\circ } \\ {\mathrm{E}}_{\mathrm{cell}}^{\circ }=-2.37-\left(-1.66\right) \\ {\mathrm{E}}_{\mathrm{cell}}^{\circ }=-0.71\mathrm{V} \end{gathered}$$

So, Al is at the cathode and not at the anode. Hence, the statement is false.

verifying whether (d) is true or not

For most metal electrodes, Electrons flow from lower ion concentration to higher ion concentration. But in some cases like Ag AgCl cells, the electron flows oppositely. Hence, the statement is true.

verifying whether (e) is true or not

The flow of negative ions is In the opposite direction to the flow of electrons. Hence, the statement is false.