I am unable to understand the folowing statement of Wikipedia it is about standard hydrogen electrode :The concentration of both the reduced form and oxidised form is maintained at unity. That implies that the pressure of hydrogen gas is 1 bar. But why if I apply ideal gas equation then I am getting molarity of nearly 0.004M .this is condradiction to the statement in Wikipedia. N/V=P/RT THEREFORE M=N/V~0.004