Electrolysis of solutions: description, application

Electrolysis refers to a process characterized by oxidation-reduction properties with respect to constituent elements of salts and other compounds in melts or solutions when electric current passes through them.

By means of electrolysis, it is possible to produce metals and non-metals characterized by a high degree of chemical purity. This reaction is simple and affordable, it can even be modeled at home. To do this, you need some source of constant electric current, a pair of electrodes and a pre-prepared electrolyte. The most basic property of electrolytes is their ability to conduct electric current.

There are electrolysis of solutions and melts of salts, with a general similarity they have a number of significant differences. Carrying out the electrolysis of solutions, it is necessary to take into account the participation of the solvent in the process. Electrolysis of melts is characterized by the presence of only the ions of the substance itself.

To obtain the desired product (whether it is metal, gas or some non-metal), it is necessary to worry about the selection of a suitable electrode and the preparation of a suitable electrolyte.

The material for the electrodes can be any conductor of electric current. In most cases, metals and alloys are used, among nonmetals, graphite rods (carbon) can show good indicators as an electrode. Very rarely, but technological solutions are known in which liquids serve as electrodes for electrodes.

Everything is ready to carry out electrolysis of solutions of salts. The positive electrode was called the anode. For the negative electrode, the designation is the cathode. Carrying out electrolysis of solutions, the anode is oxidized (dissolved), and the cathode is restored. It is very important that the dissolution of the anode does not affect the chemical process that takes place in the solution (melt). Otherwise, the main condition for the anode is its inertness. Ideally, it can be made from platinum, but graphite (carbon) anodes are also very effective.

For a cathode, almost any metal plate will fit (it will not dissolve). Copper, brass, carbon (graphite), zinc, iron, aluminum cathodes are widely used in modern industry.

Carrying out the electrolysis of solutions at home, practically from the improvised materials it is possible to obtain such substances as oxygen, chlorine, hydrogen, copper, weak acid or alkali, sulfur. Do not abuse experiments with chlorine - it is toxic!

To obtain oxygen and hydrogen, it is necessary to subject the solution of baking soda to electrolysis (alternatively - soda ash). Near the "+" electrode (anode) oxygen is released in the form of bubbles, and hydrogen ("-") near the cathode. When asked why the recovery of hydrogen, rather than sodium, occurred, as one might suppose, one can find the answer: in the series of metal stress Na is located to the left of H2, respectively, in the competition of two cations, hydrogen has won over sodium. On the example of this reaction, we witnessed how electrolysis of solutions, in fact, turned into electrolysis of a solvent (water).

Using a solution of copper sulfate in the quality of the electrolyte , we get a dark red coating on the cathode, which is pure metal, reduced by copper.

By results of carrying out of two experiments on electrolysis it is possible to make some generalizations. A positive anode becomes a place for the recovery of anions, in both of the cases considered above, it turned out to be oxygen. At the cathode, cations are restored, in our experiments they turned out to be hydrogen - in the first case, copper - in the second. As a rule, cations are metals or hydrogen, but in some cases they may be nonmetals and gases. The degree of oxidation of the element plays an important role in the recovery process.