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Ch.4 - Reactions in Aqueous Solution
Chapter 4, Problem 63

A galvanic cell is constructed from a Zn/Zn2+ half-cell (anode) and a Cl2/Cl- half-cell (cathode). (b) Write balanced equations for the electrode and overall cell reactions.

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Identify the oxidation and reduction half-reactions. For the Zn/Zn^{2+} half-cell, zinc is oxidized: Zn(s) \rightarrow Zn^{2+}(aq) + 2e^{-}. For the Cl_2/Cl^{-} half-cell, chlorine is reduced: Cl_2(g) + 2e^{-} \rightarrow 2Cl^{-}(aq).
Write the oxidation half-reaction: Zn(s) \rightarrow Zn^{2+}(aq) + 2e^{-}.
Write the reduction half-reaction: Cl_2(g) + 2e^{-} \rightarrow 2Cl^{-}(aq).
Combine the oxidation and reduction half-reactions to write the overall balanced cell reaction. Ensure that the electrons cancel out: Zn(s) + Cl_2(g) \rightarrow Zn^{2+}(aq) + 2Cl^{-}(aq).
Verify that the number of atoms and charges are balanced on both sides of the overall equation.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Galvanic Cell

A galvanic cell is an electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two half-cells, each containing an electrode and an electrolyte. The anode is where oxidation occurs, while the cathode is where reduction takes place. The flow of electrons from the anode to the cathode generates an electric current.
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Oxidation and Reduction

Oxidation and reduction are complementary processes in redox reactions. Oxidation involves the loss of electrons, leading to an increase in oxidation state, while reduction involves the gain of electrons, resulting in a decrease in oxidation state. In the context of the galvanic cell, zinc (Zn) is oxidized to Zn2+ at the anode, and chlorine (Cl2) is reduced to Cl- at the cathode.
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Balanced Chemical Equations

Balanced chemical equations represent the conservation of mass in a chemical reaction, ensuring that the number of atoms for each element is the same on both sides of the equation. For galvanic cells, it is essential to write balanced equations for both half-reactions and the overall cell reaction. This involves adjusting coefficients to balance the number of electrons transferred, as well as the reactants and products involved.
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