A voltaic cell utilizes the following reaction: 4 Fe2+1aq2 + O21g2 + 4 H+1aq2 ¡ 4 Fe3+1aq2 + 2 H2O1l2 (a) What is the emf of this cell under standard conditions?

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The given overall reaction can be split into two half-reactions. The oxidation half-reaction involves Fe^{2+} being oxidized to Fe^{3+}, and the reduction half-reaction involves O_2 being reduced to H_2O.

The oxidation half-reaction is: 4 \text{Fe}^{2+} \rightarrow 4 \text{Fe}^{3+} + 4e^{-}.

The reduction half-reaction is: O_2 + 4H^{+} + 4e^{-} \rightarrow 2H_2O.

Look up the standard reduction potentials (E^\circ) for each half-reaction in a standard reduction potential table. The standard reduction potential for Fe^{3+}/Fe^{2+} and O_2/H_2O will be needed.

Use the formula E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode}, where the cathode is the reduction half-reaction and the anode is the oxidation half-reaction.>

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Key Concepts

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

Electrochemical Cells

Electrochemical cells are devices that convert chemical energy into electrical energy through redox reactions. A voltaic cell, specifically, generates electricity spontaneously from a chemical reaction, involving oxidation and reduction processes occurring in separate half-cells. Understanding the structure and function of these cells is crucial for analyzing their emf (electromotive force) and overall efficiency.

Standard Electrode Potentials

Standard electrode potentials are measured voltages that indicate the tendency of a species to be reduced, measured under standard conditions (1 M concentration, 1 atm pressure, and 25°C). These values are essential for calculating the emf of a voltaic cell using the Nernst equation or by subtracting the reduction potential of the anode from that of the cathode. Knowing these potentials allows for the prediction of the direction of electron flow in the cell.

Nernst Equation

The Nernst equation relates the emf of an electrochemical cell to the standard electrode potentials and the concentrations of the reactants and products. It is expressed as E = E° - (RT/nF) ln(Q), where E° is the standard emf, R is the gas constant, T is the temperature in Kelvin, n is the number of moles of electrons transferred, F is Faraday's constant, and Q is the reaction quotient. This equation is vital for calculating the emf under non-standard conditions.

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Textbook Question

A voltaic cell utilizes the following reaction: 4 Fe2+1aq2 + O21g2 + 4 H+1aq2 ¡ 4 Fe3+1aq2 + 2 H2O1l2 (b) What is the emf of this cell when 3Fe2+4 = 1.3 M, 3Fe3+4= 0.010 M, PO2 = 0.50 atm, and the pH of the solution in the cathode half-cell is 3.50?

Textbook Question

A voltaic cell utilizes the following reaction: 2 Fe3+1aq2 + H21g2 ¡ 2 Fe2+1aq2 + 2 H+1aq2 (a) What is the emf of this cell under standard conditions?

Textbook Question

A voltaic cell utilizes the following reaction: (b) What is the emf for this cell when 3Fe3+4 = 3.50 M, PH2= 0.95 atm, 3Fe2+4 = 0.0010 M, and the pH in both half-cells is 4.00?

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