14.15 (b)

[Carrie Huang 2F]

14.15 (b) states: Write the half-reactions and devise a galvanic cell (write a cell diagram) to study each of the following reactions:
(b) H+(aq) + OH-(aq) ---> H2O(l), the Brønsted neutralization reaction

I am looking at the solutions manual and I am really confused. Can someone explain in detail how to get to the final answer (including how to get the half-reactions)?

[Chem_Mod]

We're looking for half reactions involving H₂O, H⁺, and OH^-. A good option could be using the reactions suggested in the solutions manual, but this isn't our only choice. Just going by the solution manual, they started with the reduction on O₂ gas in acidic conditions (our H⁺). Logically, we need to cancel out the O₂ gas in the oxidation reaction because it doesn't appear in our desired reaction. Another reaction involving O₂ gas is the oxidation of OH^-, perfect for what we need. Since that will be our oxidation half reaction, we need to flip the sign of the E⁰ i.e. -0.40 V, so E⁰_cell will be 1.23 V + (-0.40 V) = 0.83 V



Notice that this same result could have been obtained by the reduction of H⁺, E⁰ 0.0 V, and the oxidation of hydrogen gas to water, E⁰_red = -0.83 V and E⁰_cell = 0 + 0.83 V = 0.83 V

[sandyh9711]

Will these equations be given to us, so we know what equations to base our work on?