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SYMBOLS

C = Concentration (gram-equivalents per litre).
E = Electromotive force.
E. = Electro-affinity (see p. 158).
F= Faraday (see p. 3).
K = Reaction (or ionisation) constant (see p. 76).
L = Latent heat (see p. 178).
Q = Heat of reaction (see pp. 154 and 179).
R = Gas constant (8·316 joules per mol).

T = Absolute temperature.
uc = Mobility of anion and cation (see p. 43).
W = Work (see p. 179).

A = Equivalent conductivity (see p. 58). un = Temperature coefficient of electromotive force.

dE

i = van't Hoff's factor (see p. 70). la lc = Ionic conductivity of anion and cation (see p. 62).

r= Valency.

t = Temperature (Centigrade). WA Uc = Velocity of anion and cation.

v = Dilution (c.c. per gram-equivalent).
x = Migration ratio of anion (see p. 35).
y = Degree of Ionisation (see p. 71).

= Concentration (gram-equivalents per c.c.).
K = Electric conductivity.

ELECTRO-CHEMISTRY

CHAPTER I

MECHANISM OF CONDUCTION IN ELECTROLYTES

$ 1. FARADAY'S LAWS: MEASUREMENT OF

QUANTITY OF ELECTRICITY

d through the electrolytes ; tihe in electrolysis such

THERE is a group of substances which, when an electric current is passed through them, suffer chemical decomposition. These substances are called electrolytes ; the process of decomposition electrolysis ; and reactions occurring in electrolysis may be described as electro-chemical. It is the study of such electro-chemical reactions that forms the subject of the present book.

As a typical process of electrolysis we may take the decomposition of dilute sulphuric acid between platinum plates. Imagine, then, this arrangement of apparatus (Fig. 1)—Place some dilute + 1 sulphuric acid in a beaker; insert into it two plates of platinum, so as to be partially immersed, taking care that they do not touch each other; con- . nect the upper parts of the plates by wires to a source of electric current (battery, dynamo, thermopile, etc.). Such an arrangement is known as an

Fig. 1. electrolytic cell. The platinum plates serve to convey the current into and out of the liquid, and are called electrodes ; that by which the current is led in, the anode,

T. P. C.

VAMA

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