electrolyte is always a certain amount of ions with the characters "plus" and "minus", prepared by the reaction of molecules of dissolved substances with a solvent.When it occurs in an electric field, ions start to move to the electrodes, a positive direct to the cathode, negative - to the anode.After reaching the electrodes, the ions give them their charges are converted into neutral atoms and are deposited on the electrodes.The more suitable ions to the electrodes, the greater will be delayed for the substances.
to this conclusion we can come and empirically.Passing a current through an aqueous solution of copper sulfate and will be watching the release of copper cathode in the coal.We find that it is first covered with a copper layer barely noticeable, then, as it is passing a current will increase, and by prolonged passage of current available at the carbon electrode layer of copper is of considerable thickness, which is easy to solder, such as copper wire.
phenomenon of release of a substance on the electrodes while current passing through the electrolyte is called electrolysis.
electrolysis pass through various different currents and carefully measuring the mass of a substance released at the electrodes of each of the electrolyte, the English physicist Faraday in 1833 - 1834.I opened two laws for electrolysis.
first Faraday's law establishes the relationship between the mass of the extracted material during electrolysis and the amount of charge that has passed through the electrolyte.
This law is formulated as follows: the mass of matter, which stood out in the electrolysis for each electrode is directly proportional to the amount of charge that has passed through the electrolyte:
m = kq,
where m - mass of matter, which are marked, q - charge.
magnitude k - elektrohimicheskimy equivalent substance.It is typical for each substance released by the electrolyte.
If you take the formula q = 1 Coulomb, then k = m, ie,electrochemical equivalent of the substance will be numerically equal to the mass of substances extracted from the electrolyte during the passage of the charge in a pendant.
expressed in the formula via a charge current I and time t, we obtain:
m = kIt.
first Faraday's law is tested by experience as follows.Passing a current through the electrolytes A, B and C. If they are the same, the masses of the selected substance in the A, B and C will be treated as the currents I, I1, I2.The number of substances selected in A will be equal to the sum of volumes allocated to B and C, since the current I = I1 + I2.
second Faraday's law establishes the dependence of the electrochemical equivalent of the atomic weight of the substance and its valence, and is formulated as follows: electrochemical equivalent of the substance will be proportional to their atomic weight, and inversely proportional to its valence.
atomic weight ratio of substance to its valence is called the chemical equivalent of the substance.By entering this value, the second Faraday's law can be formulated differently: the electrochemical equivalent of the substance are proportional to their own chemical equivalents.Let
electrochemical equivalents of different substances are respectively k1 and k2, k3, ..., kn, the chemical equivalents of the same substances x1 and x2, x23, ..., xn, then k1 / k2 = x1 / x2, or k1 / x1 = k2/ x2 = k3 / x3 = ... = kn / xn.
In other words, the ratio of the electrochemical equivalent of the substance to the amount of the same substance is a constant for all substances having the same value:
k / x = c.
It follows that the ratio k / x is constant for all substances:
k / x = c = 0, 01036 (meq) / k.
quantity c shows how milligram equivalents of substance released at the electrodes during the passage through the electrolyte of electric charge, equal to 1 coulomb.The second law of Faraday represented by the formula:
k = cx.
Substituting this expression for k in the first law of Faraday, the two can be combined in a single expression:
m = kq = cxq = cxIt,
where a - a universal constant equal to 0, 00001036 (eq) / k.
This formula shows that by passing the same current for the same period of time in two different electrolytes, we isolate electrolytes of both the amount of substances relating to both chemical equivalents thereof.
Since x = A / n, we can write:
m = cA / nIt,
ie, the mass of substances extracted at the electrodes during electrolysis is directly proportional to its atomic weight, current, time, and vice versaproportional valency.
second Faraday's law for electrolysis, as well as the first, follows directly from the nature of the ion current in the solution.
Faraday's Law, Lenz, as well as many other prominent physicists played a huge role in the history and development of physics.
