Sketch the galvanic cells based on the following overall reactions. Show the direction of electron flow, and identify the cathode and anode. Give the overall balanced equation. Assume that all concentrations are \(1.0 \mathrm{M}\) and that all partial pressures are \(1.0 \mathrm{~atm}\). a. \(\mathrm{Cr}^{3+}(a q)+\mathrm{Cl}_{2}(g) \rightleftharpoons \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+\mathrm{Cl}^{-}(a q)\) b. \(\mathrm{Cu}^{2+}(a q)+\mathrm{Mg}(s) \rightleftharpoons \mathrm{Mg}^{2+}(a q)+\mathrm{Cu}(s)\)

Short Answer

Expert verified
a. In the galvanic cell for the chromium and chlorine reaction, the cathode is the reduction half-reaction: \(2Cr^{3+}(aq) + 7H_2O(l) \rightarrow Cr_2O_7^{2-}(aq) + 14H^+(aq) + 6e^-\), and the anode is the oxidation half-reaction: \(2Cl^-(aq) \rightarrow Cl_2(g) + 2e^-\). The overall balanced equation is: \(2Cr^{3+}(aq) + 2Cl^-(aq) + 7H_2O(l) \rightleftharpoons Cr_2O_7^{2-}(aq) + Cl_2(g) + 14H^+(aq)\). b. For the copper and magnesium reaction, the cathode is the reduction half-reaction: \(Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)\), and the anode is the oxidation half-reaction: \(Mg(s) \rightarrow Mg^{2+}(aq) + 2e^-\). The overall balanced equation is: \(Cu^{2+}(aq) + Mg(s) \rightleftharpoons Mg^{2+}(aq) + Cu(s)\).

Step by step solution

01

1. Identify the half-reactions

To identify the half-reactions, we'll first split the overall reaction into separate reduction and oxidation processes: \(Cr^{3+}(aq) \rightarrow Cr_2O_7^{2-}(aq)\) \(Cl_2(g) \rightarrow Cl^-(aq)\)
02

2. Determine electron flow and balance the half-reactions

Next, we will balance the half-reactions and identify the direction of electron flow. After balancing the half-reactions, we have: \(2Cr^{3+}(aq) + 7H_2O(l) \rightarrow Cr_2O_7^{2-}(aq) + 14H^+(aq) + 6e^-\) (Reduction) \(2Cl^-(aq) \rightarrow Cl_2(g) + 2e^-\) (Oxidation)
03

3. Identify the cathode and anode

In a galvanic cell, reduction occurs at the cathode and oxidation occurs at the anode. Therefore, for this reaction: Cathode: \(2Cr^{3+}(aq) + 7H_2O(l) \rightarrow Cr_2O_7^{2-}(aq) + 14H^+(aq) + 6e^-\) Anode: \(2Cl^-(aq) \rightarrow Cl_2(g) + 2e^-\)
04

4. Overall balanced equation

Finally, by combining the balanced half-reactions, we find the overall balanced equation: \(2Cr^{3+}(aq) + 2Cl^-(aq) + 7H_2O(l) \rightleftharpoons Cr_2O_7^{2-}(aq) + Cl_2(g) + 14H^+(aq)\) #b. Copper and Magnesium reaction#
05

1. Identify the half-reactions

We will start by splitting the overall reaction into separate reduction and oxidation processes: \(Cu^{2+}(aq) \rightarrow Cu(s)\) \(Mg(s) \rightarrow Mg^{2+}(aq)\)
06

2. Determine electron flow and balance the half-reactions

Next, we will balance the half-reactions, and identify the direction of electron flow: \(Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)\) (Reduction) \(Mg(s) \rightarrow Mg^{2+}(aq) + 2e^-\) (Oxidation)
07

3. Identify the cathode and anode

In a galvanic cell, reduction occurs at the cathode and oxidation occurs at the anode. Therefore, for this reaction: Cathode: \(Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)\) Anode: \(Mg(s) \rightarrow Mg^{2+}(aq) + 2e^-\)
08

4. Overall balanced equation

Lastly, by combining the balanced half-reactions, we find the overall balanced equation: \(Cu^{2+}(aq) + Mg(s) \rightleftharpoons Mg^{2+}(aq) + Cu(s)\)

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Most popular questions from this chapter

Which of the following statement(s) is/are true? a. Copper metal can be oxidized by \(\mathrm{Ag}^{+}\) (at standard conditions). b. In a galvanic cell the oxidizing agent in the cell reaction is present at the anode. c. In a cell using the half reactions \(\mathrm{Al}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Al}\) and \(\mathrm{Mg}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Mg}\), aluminum functions as the anode. d. In a concentration cell electrons always flow from the compartment with the lower ion concentration to the compartment with the higher ion concentration. e. In a galvanic cell the negative ions in the salt bridge flow in the same direction as the electrons.

Consider the electrolysis of a molten salt of some metal. What information must you know to calculate the mass of metal plated out in the electrolytic cell?

The following standard reduction potentials have been det mined for the aqueous chemistry of indium: $$ \begin{array}{cl} \mathrm{In}^{3+}(a q)+2 \mathrm{e}^{-} \longrightarrow \operatorname{In}^{+}(a q) & \mathscr{E}^{\circ}=-0.444 \mathrm{~V} \\ \mathrm{In}^{+}(a q)+\mathrm{e}^{-} \longrightarrow \operatorname{In}(s) & \mathscr{E}^{\circ}=-0.126 \mathrm{~V} \end{array} $$ a. What is the equilibrium constant for the disproportionation reaction, where a species is both oxidized and reduced, shown below? $$ 3 \operatorname{In}^{+}(a q) \longrightarrow 2 \operatorname{In}(s)+\operatorname{In}^{3+}(a q) $$ b. What is \(\Delta G_{\mathrm{f}}^{\circ}\) for \(\operatorname{In}^{+}(a q)\) if \(\Delta G_{\mathrm{f}}^{\circ}=-97.9 \mathrm{~kJ} / \mathrm{mol}\) for \(\mathrm{In}^{3+}(a q) ?\)

Consider the following half-reactions: $$ \begin{aligned} \mathrm{Pt}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt} & \mathscr{E}^{\circ} &=1.188 \mathrm{~V} \\ \mathrm{PtCl}_{4}^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt}+4 \mathrm{Cl}^{-} & \mathscr{E}^{\circ} &=0.755 \mathrm{~V} \\ \mathrm{NO}_{3}^{-}+4 \mathrm{H}^{+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{NO}+2 \mathrm{H}_{2} \mathrm{O} & \mathscr{E}^{\circ} &=0.96 \mathrm{~V} \end{aligned} $$ Explain why platinum metal will dissolve in aqua regia (a mixture of hydrochloric and nitric acids) but not in either concentrated nitric or concentrated hydrochloric acid individually.

Sketch the galvanic cells based on the following half-reactions. Show the direction of electron flow, show the direction of ion migration through the salt bridge, and identify the cathode and anode. Give the overall balanced equation, and determine \(\mathscr{E}^{\circ}\) for the galvanic cells. Assume that all concentrations are \(1.0 M\) and that all partial pressures are \(1.0 \mathrm{~atm}\). a. \(\mathrm{Cl}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cl}^{-} \quad \mathscr{E}^{\circ}=1.36 \mathrm{~V}\) \(\mathrm{Br}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Br}^{-} \quad \mathscr{8}^{\circ}=1.09 \mathrm{~V}\) b. \(\mathrm{MnO}_{4}^{-}+8 \mathrm{H}^{+}+5 \mathrm{e}^{-} \rightarrow \mathrm{Mn}^{2+}+4 \mathrm{H}_{2} \mathrm{O} \quad \mathscr{C}^{\circ}=1.51 \mathrm{~V}\) \(\mathrm{IO}_{4}^{-}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{IO}_{3}^{-}+\mathrm{H}_{2} \mathrm{O} \quad \mathscr{E}^{\circ}=1.60 \mathrm{~V}\)

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