Ahydrogen electrode can, in principle, be used to monitor changes in the molar concentrations of weak acids in biologically active solutions. consider a hydrogen electrode in a solution of lactic acid as part of an overall galvanic cell at 25°c and 1 bar. estimate the change in the electrode potential when the concentration of lactic acid in the solution is changed from 5.0 mmol l-1 to 25.0 mmol l-1.