Pressure dependence hydrogen activation

The authors then chose to examine hydrogen adsorption at Cu(110). This was a well-chosen example in that hydrogen adsorption is activated, being pressure dependent, and also was already known from LEED studies to exhibit a missing row (1 x 2) structure with every second close packed (110) copper row missing at high hydrogen pressures. What, then, was learnt from STM ... 

The pressure dependence of the reaction between butane-1-thiol and hydrogen atoms at 133, 266, 532, 2660, and 5320 Pa, using two types of fast-flow discharge reactors, have been studied. Butane and but-l-ene were the main products. Pressure dependence indicated decomposition through vibrationally activated species. 

Hydrogen pressure dependencies nj7 were fit in steps 6 to 10, using the same sequence as in steps 1 to 5. Data for nn determination were at 756 K and H2 partial pressures of 827 and 2619 kPa. The activation energies Efi were fit similarly in steps 11 to 15 by using data at 1226 kPa H2 partial pressure and 727 and 794 K temperatures. This procedure completed determination of the selectivity matrix K. 

Activation energy (kcal/mole) Hydrogen pressure dependence... 

Thus the potential of the hydrogen electrode depends on the hydrogen-ion concentration in the solution and on the pressure of hydrogen gas above the solution. The standard potential, E9, can be measured in a system where the activity of hydrogen ions is unity in the solution and the pressure of hydrogen gas over the solution is 1 atm. We have seen that the standard potential, B, of such an electrode is by definition 0. 

---