Oxidation of Dissolved Dihydrogen

In turn, the clean surface reacts with a second H2 to form two Pt—H bonds  

The value of Kis estimated on the basis of the Pt—H bond-formation energy from metallic platinum [A(—AG p), 203 kJ mol-1 Eq. (8.7)] and the dissociative bond energy for H2(AGDBE, —402 kJ mol-1). 

This activated platinum-electrode system is the equivalent of an NHE, and therefore conforms to the Nemst expression of Eq. (8.2). Rearrangement gives 

In the presence of Pt—H(s) (and H2), this process is facilitated via direct formation of an H—OH bond 

Addition of the Pt—H(s) bond eneigy [A(—AGBF) = 203 kJ mol-1, Eq. (8.7)] to the differential bond-formation energy for H—OH gives an electrochemical measure of the HO—H bond eneigy [—AGBF = 465.7 kJ mol-1 (literature value, 465.3 kJ mol-1)3]. 

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