Pressure Jump Apparatus for the Study of Fast Reactions

Abstract

Fabrication of a new pressure jump cell made entirely from Plexiglas is described. Chemical relaxation effects greater than 50 jusec can be measured when the pressure on a chemical system is suddenly released from 40 atm by means of a bursting phosphor-bronze diaphragm and the resulting conductance change is measured by a Wheatstone bridge arrangement.

Kinetics of selenate and selenite adsorption/desorption at the goethite/water interface

“…which can be further simplified if only small equilibrium perturbations are considered, i.e., small x. Then the last two terms in eq 26 become vanishingly small leading to (27) From the definition of relaxation time Accordingly, the reciprocal relaxation time r'1 can be defined as…”

“…The second step involves a ligand-exchange process, whereby the adsorbed selenite enters the a layer and replaces a ligand from the goethite surface to form the inner-sphere surface complexes (XHSe03°a nd XSe03~). The two protolytic equilibria (represented by K5 and Ke and shown by vertical arrows between the complexes in eq 33) are established rapidly compared to the complexation reactions (25)(26)(27).…”

Kinetic aspects of analytical chemistry

“…There have been several papers on improved instrumentation in relaxation methods for measuring fast reaction. An improved pressure-jump apparatus has been described by Knoche and Wiese (164) and Patel and coworkers (165). Kruzan and Stoehlon have devised a relatively simply digitizing interface for use in relaxation experiments to improve sampling and give on-line processing of the data (166) .…”