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Ch.20 - Electrochemistry
All textbooksBrown 14th EditionCh.20 - ElectrochemistryProblem 74a
Chapter 20, Problem 74a

During the discharge of an alkaline battery, 4.50 g of Zn is consumed at the anode of the battery. (a) What mass of MnO2 is reduced at the cathode during this discharge?

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1
Identify the balanced chemical reaction for the discharge of an alkaline battery. Typically, the reaction involves zinc (Zn) being oxidized at the anode and manganese dioxide (MnO2) being reduced at the cathode.
Write the half-reactions for the anode and cathode. The anode reaction is Zn -> Zn^2+ + 2e^-. The cathode reaction is MnO2 + H2O + e^- -> Mn(OH)2 + OH^-.
Determine the molar mass of Zn and MnO2. The molar mass of Zn is approximately 65.38 g/mol, and the molar mass of MnO2 is approximately 86.94 g/mol.
Calculate the moles of Zn consumed using the given mass (4.50 g) and its molar mass. Use the formula: moles of Zn = mass of Zn / molar mass of Zn.
Use stoichiometry to find the moles of MnO2 reduced. According to the balanced reaction, 1 mole of Zn corresponds to 1 mole of MnO2. Then, calculate the mass of MnO2 reduced using its molar mass and the moles of MnO2 obtained from stoichiometry.

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Textbook Question

During the discharge of an alkaline battery, 4.50 g of Zn is consumed at the anode of the battery. (b) How many coulombs of electrical charge are transferred from Zn to MnO2?

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