(b) Using the standard reduction potentials in Appendix E, calculate the standard voltage generated by the hydrogen fuel cell in acidic solution.

Verified step by step guidance

1. Identify the half-reactions involved in the hydrogen fuel cell. In an acidic solution, the reactions are: the oxidation of hydrogen (H₂) and the reduction of oxygen (O₂).
2. Write the half-reactions: Oxidation half-reaction: H₂ → 2H⁺ + 2e⁻. Reduction half-reaction: O₂ + 4H⁺ + 4e⁻ → 2H₂O.
3. Look up the standard reduction potentials (E°) for each half-reaction in Appendix E. Note that the standard reduction potential for the oxidation reaction will be the negative of the value listed, as it is written as a reduction.
4. Calculate the standard cell potential (E°cell) using the formula: E°cell = E°(cathode) - E°(anode). Substitute the values from the standard reduction potentials you found.
5. Ensure that the overall cell reaction is balanced in terms of both mass and charge, and verify that the calculated E°cell is positive, indicating a spontaneous reaction under standard conditions.

Key Concepts

Standard Reduction Potentials

Standard reduction potentials are measured voltages that indicate the tendency of a chemical species to gain electrons and be reduced. These values are typically listed in tables and are measured under standard conditions (1 M concentration, 1 atm pressure, and 25°C). The more positive the standard reduction potential, the greater the species' ability to be reduced. In the context of electrochemical cells, these potentials are crucial for calculating the overall cell voltage.

Hydrogen Fuel Cell Reaction

A hydrogen fuel cell generates electricity through the electrochemical reaction between hydrogen and oxygen, producing water as a byproduct. In acidic solutions, hydrogen ions (H+) and electrons are produced at the anode, while oxygen is reduced at the cathode. The overall reaction can be simplified to 2H2 + O2 → 2H2O, and the standard reduction potentials for the half-reactions involved are essential for determining the cell's voltage.

Nernst Equation

The Nernst equation relates the cell potential to the standard reduction potential and the concentrations of the reactants and products. It accounts for non-standard conditions and allows for the calculation of the actual cell voltage under varying concentrations. The equation is given by E = E° - (RT/nF) ln(Q), where E° is the standard potential, 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.