EEACTIONS OF OXIDATION AND REDUCTION 123to another; metathesis involves no transfer of charges, but simply a
regrouping of the charged radicals.
The simplest type of oxidation and reduction reaction is that
which involves merely the charging and discharging of simple
ions. The course of such a reaction can be predicted from a
knowledge of where the elements concerned stand in the electro-
motive series.PROBLEMS
In the left-hand column state the observable effect and in the
right-hand column write the fully ionized equations.- Fe (metal) + CuSO 4.
- Zn (metal) + HC1.
- Cu (metal) + HC1.
- Ag (metal) + AuCl 3.
- Cu (metal) + PtCU-
- AgCl (finely divided solid) + Zn (zinc dust) suspended
in water. - Ag (in a photographic print) + PtCl^
- FeCl 2 + Cl 2.
- CuCl (solid) + Cl 2.
- Na (metal) + H 2 O.
FARADAY'S LAW
Let us consider an electric circuit consisting of a dynamo and
metallic conductors connecting the poles of the dynamo to the two
poles of an electrolytic cell. The same amount of electricity flows
through every section of the circuit, but the mechanism by which
the current passes in the different parts of the circuit is of three
different kinds:
(1) Through the metallic conductor the current passes without
any alteration of the conductor. The electrons, which may be
regarded as atoms of negative electricity, simply pass through the
metallic mass without dislocating the atoms of the metal. (2)
Through the electrolytic conductor the current passes solely by the
movement of positive and negative ions in opposite directions.
(3) At the surface of the electrode electrons are transferred to or
from the atoms or ions at that surface. This involves a change of
valence, and at the cathode, which is the electrode at which elec-