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Ch.19 - Electrochemistry
Chapter 19, Problem 119

Write a balanced equation for the overall cell reaction when a lead storage battery is being charged. Refer to Section 19.10.

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Identify the half-reactions involved in a lead storage battery. During charging, the reactions are reversed compared to discharging. The discharging reactions are: \( \text{Pb} + \text{PbO}_2 + 2\text{H}_2\text{SO}_4 \rightarrow 2\text{PbSO}_4 + 2\text{H}_2\text{O} \).
Reverse the discharging reactions to represent the charging process. The half-reactions for charging are: \( \text{PbSO}_4 + 2\text{e}^- + 2\text{H}^+ \rightarrow \text{Pb} + \text{H}_2\text{SO}_4 \) and \( \text{PbSO}_4 + 2\text{H}_2\text{O} \rightarrow \text{PbO}_2 + 4\text{H}^+ + 2\text{e}^- + \text{SO}_4^{2-} \).
Balance the electrons in the half-reactions. Ensure that the number of electrons lost in the oxidation half-reaction equals the number of electrons gained in the reduction half-reaction.
Combine the balanced half-reactions to form the overall balanced equation for the charging process. This involves adding the two half-reactions together and canceling out the electrons and any other species that appear on both sides of the equation.
Verify that the final equation is balanced in terms of both mass and charge. Check that the number of each type of atom and the total charge are the same on both sides of the equation.

Key Concepts

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

Redox Reactions

Redox reactions involve the transfer of electrons between two species, resulting in oxidation (loss of electrons) and reduction (gain of electrons). In the context of a lead storage battery, the charging process is a redox reaction where lead sulfate is converted back to lead and lead dioxide, facilitating the storage of electrical energy.
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Electrochemical Cells

Electrochemical cells convert chemical energy into electrical energy through redox reactions. A lead storage battery is a type of electrochemical cell that operates in two half-cells, where oxidation occurs at the anode and reduction at the cathode. Understanding the structure and function of these cells is essential for writing balanced equations for their reactions.
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Balancing Chemical Equations

Balancing chemical equations ensures that the number of atoms for each element is the same on both sides of the equation, adhering to the law of conservation of mass. In the case of the lead storage battery, balancing the equation involves accounting for all reactants and products, including lead, lead dioxide, and sulfuric acid, to accurately represent the overall cell reaction during charging.
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Related Practice
Textbook Question
The following galvanic cell has a potential of 1.214 V at 25 °C: Calculate the value of Ksp for Hg2Br2 at 25°C
Textbook Question
For the following half-reaction, E° = 1.103 V: Calculate the formation constant Kf for Cu(CN)2-.
Textbook Question
Write a balanced equation for the overall cell reaction when a lead storage battery is being charged. Refer to Section 19.10.
Textbook Question

You are on your dream vacation at the beach when a major storm knocks out the power for days. Your cell phone is dead, and you want to make a battery to charge it. You find the following materials in the beach house. blue stone algaecide for pools, which can be used to make a 1.0 M Cu2+ solution alum in the kitchen, which can be used to make a 1.0 M Al3+ solution aluminum foil, copper wire, and bologna, which can be used as a salt bridge. (b) What voltage can be generated?

Textbook Question

You are on your dream vacation at the beach when a major storm knocks out the power for days. Your cell phone is dead, and you want to make a battery to charge it. You find the following materials in the beach house. blue stone algaecide for pools, which can be used to make a 1.0 M Cu2+ solution alum in the kitchen, which can be used to make a 1.0 M Al3+ solution aluminum foil, copper wire, and bologna, which can be used as a salt bridge. (d) An iPhone requires 5.0 V for charging. Can this battery charge the phone? Explain.

Textbook Question

A storm has knocked out power to your beach house, and you would like to build a battery from household items to charge your iPhone. You have the following materials. alum in the kitchen, which can be used to make a 1.0 M Al3+ solution bleach, which is a solution that is approximately a 1.0 M in ClO-aluminum foil, a platinum necklace and bologna, which can be used as a salt bridge (a) What are the half-reactions and overall reaction in the battery?