Overview
A water sample with a pH of 7.8 (measured in the field) was later recorded to have a pH of 10.2 (in the lab). The oxygen concentration in the sample bottle headspace increased from 21% (in the field) to 40% (in the lab).
Assuming that the reduction of O2 is taking place in this glass bottle and is governed by the following half-reaction:
4e- + 4H+ + O2 <-> 2H2O
pEo=20.8
1. Derive the pe equation corresponding to this half-redox chemical reaction. (Utilize Keq)
2. Using the determined equation, calculate the pe values corresponding to field conditions, and lab conditions.
3. Determined the concentrations of dissolved oxygen (O2(aq)) in units of mol/L and mg/L in the water sample under field and lab conditions.