Page 36 - MODERN ASPECTS OF ELECTROCHEMISTRY

23
Voltaic Cells in Electrochemistry and Surface Chemistry of Liquids
potentials at the two liquids are different, the Volta electric field exists in
the gap between them.= The droplets carry away the charge on the jet, so
that there must be a continuous flow of charge into the jet.= If this is
connected, via suitable reference electrodes, to a high-impedance elec-
trometering system, as in the ionizing method, and the liquid surrounding
the jet is connected to a potentiometer, a condition may be established in
which the outer potential of the jet equals that of the surrounding liquid.
The continuous renewing of the surface, which is the principal virtue of
the jet method, renders the method particularly suitable for solutions that
do not contain spread monolayers.= Kamien `i has indicated that the
dynamic jet method is reproducible, the purity of a free-flowing surface
is ensured, no ionization occurs, and consequently the method is easy to
handle. The possibilityof calculating the dynamic changes of χ W from
49
the droplets’ diameter has been also suggested. 50
Experimental systems using a dynamic condenser in which the inves-
tigated solution is flowing horizontally or vertically have also been
designed. 51

V. VOLTA POTENTIAL OF THE METAL/SOLUTION
INTERFACð
The Volta potential at the metal/solution interface [Fig. 2, Eqs.=(3) and (4)]
may be described by the equation
∆ Ψ=g (ion)+δ M (S) – δ M
M
M
S
S
(S)
(6)
where δ M and δ (M) are the modifications relative to those at the surfaces
S
(S)
of the separate phases and are caused bytheir physical contact and the
creation of an interface. 1,13,22,23 Such voltaic measurements also include
M
the zero charge potential [g (ion) = 0], for which the Volta potential is
S
equal to
(∆ S Ψ) =δ M –δ S
M
0 0 0 (7)
Only this equation has been used in practice.= For a mercury/water inter -
52
H g
face, the (∆ W Ψ)0 is equal to -0.25 V2,23 or -0.22 V. Its components [Eq.
(7)] have been estimated to be -0.30 V and -0.05 V, respectively. 2,23
They show that in the presence of water, the electrons cannot expand freely
as in a gas, but are pushed into mercury, and that the interaction of water