buffer the h 2 po 4 u2212 hpo 4 2 u2212 couple had a pka of 7 20 the ph thus being constant the free proton concentration at ph 8 0 was however consistently very small at 10 u2212 8 m therefore this concentration could not be responsible for the high cathode current of 13 a m u2212 2 which furthermore was much greater than the cathode current of the reference electrolyte 1 kcl 100 mm also at ph 8 0 the following examples were carried out with the same electrolysis device and according to the same operating protocol as described in the preceding example except that the electrolyses were now conducted at a constant current of u2212 13 5 a m u2212 2 on three different electrolytes whose characteristics are summarized in table 3 the electrolyses lasted 2 hours with the temperature ranging from 20 u00b0 c to 25 u00b0 c in the three experiments the production of hydrogen measured as described above was on average of the order of 10 ml hr which corresponds to a u201c raw u201d faraday efficiency of approximately 80 the change in potential across the electrolysis device denoted ecell is shown in fig3 which illustrates the change as a function of.