Galvanic element: scheme, principle of operation, application

In order to draw up a scheme of a galvanic cell, it is necessary to understand the principle of its actions, the features of the structure.

Consumers rarely pay attention to batteries and batteries, while these sources of current are the most in demand.

Chemical sources of current

What is a galvanic cell? Its scheme is based on the electrolyte. The device includes a small container, where the electrolyte is located, adsorbed by the separator material. In addition, the scheme of two galvanic elements assumes the presence of a cathode and an anode. What is the name of such a galvanic cell? A scheme that connects two metals together presupposes the presence of an oxidation-reduction reaction.

The simplest galvanic cell

It implies the presence of two plates or rods made of different metals, which are immersed in a solution of a strong electrolyte. During the operation of this galvanic cell, an oxidation process is performed at the anode, which is associated with the release of electrons.

At the cathode, a recovery accompanied by the adoption of negative particles. There is a transfer of electrons along the external circuit to the oxidant from the reducing agent.

Example of a galvanic cell

In order to compose electronic circuits of galvanic cells, it is necessary to know the value of their standard electrode potential. Let us analyze a variant of a copper-zinc galvanic cell functioning on the basis of the energy released during the interaction of copper sulfate with zinc.

This galvanic cell, the scheme of which will be given below, is called the Jacobi-Daniel element. It includes a copper plate, which is immersed in a solution of copper sulfate (copper electrode), and also it consists of a zinc plate located in a solution of its sulfate (zinc electrode). Solutions are in contact with each other, but in order to prevent them from mixing, the element uses a partition made of a porous material.

Operating principle

How does a galvanic cell function, whose circuit has the form Zn ½ ZnSO4 ½½ CuSO4 ½ Cu? During its operation, when the electrical circuit is closed, the process of oxidation of metallic zinc occurs.

On its surface of contact with a solution of salt, the conversion of atoms into cations of Zn2 + is observed. The process is accompanied by the release of "free" electrons, which move along the external circuit.

The reaction proceeding on the zinc electrode can be represented in the following form:

Zn = Zn2 + + 2e-

Recovery of metal cations is carried out on a copper electrode. Negative particles that come here from the zinc electrode are combined with copper cations, precipitating them in the form of a metal. This process has the following form:

Cu2 + + 2e- = Cu

If we combine the two reactions discussed above, we obtain a summary equation describing the work of the zinc-copper galvanic cell.

The zinc electrode acts as the anode, copper serves as the cathode. Modern galvanic cells and batteries assume the use of one solution of electrolyte, which expands the scope of their application, makes their operation more comfortable and convenient.

Varieties of galvanic cells

The most common are coal-zinc elements. They use a passive carbon collector current, in contact with the anode, which serves as the oxide of manganese (4). The electrolyte is ammonium chloride, used in pasty form.

It does not spread, so the galvanic cell itself is called dry. Its peculiarity is the possibility of "recovering" during work, which positively affects the duration of their operational period. Such galvanic cells are of low cost, but low power. When the temperature decreases, they reduce their effectiveness, and when it increases, the electrolyte dries out gradually.

Alkaline elements assume the use of an alkali solution, so they have quite a few applications.

In the lithium cells, the active metal acts as the anode, which positively affects the lifetime. Lithium has a negative electrode potential, so with small dimensions, similar elements have a maximum rated voltage. Among the shortcomings of such systems is a high price. Opening lithium current sources is explosive.

Conclusion

The principle of operation of any galvanic cell is based on oxidation-reduction processes proceeding on the cathode and anode. Depending on the metal used, the chosen electrolyte solution, the service life of the element varies, as well as the value of the rated voltage. At present, lithium, cadmium galvanic cells that have a sufficiently long service life are in demand.