Lab 2. Copper plating of the copper plate and proof of the Faraday's Law Mashtakova k.H., Ahmadiyarova z.K., Sertaeva z.O.

Objective: Conduct copper plating of parts of the copper plate in the laboratory and prove the validity of Faraday's law experimentally.

Summary: Copper plating – process copper plating layer thickness of 1 micron to 300 microns or more. Copper coatings have excellent adhesion to various metals, high ductility and conductivity. Copper coatings are easily oxidized by atmospheric conditions and are covered by oxide patina, getting brighter stains and spots of different shades. Currently, the electroplating process as a primary or an acid copper plating is one of the most common metal coating deposition processes. This coating is widely used to protect against corrosion of parts in chemical engineering, for decorative purposes, for leveling the surface or to impart the final coating of high reflective properties.

Electric current in electrolytes

Substance whose molecules dissociate into ions in solution or in molten salts called electrolytes. This process is called electrolytic dissociation. Electric current in the electrolyte is moving ions of both signs in opposite directions. Passage of current through the electrolyte constant associated with the transfer agent and accompanied by the release of components of these materials on the electrodes. That process is called electrolysis.

If you enter into the electrolyte two electrodes (metal or coal), connected to the poles of a DC voltage source, and create a constant external electric field, then under the influence of electrical forces ions in the solution will come in the direction of move. Positive ions move to the negative electrode (cathode) and negative ions – a positive electrode (anode). Reaching the electrodes, the ions are discharged: the anode anions give their excess electrons, cations are reduced at the cathode. For example, a molecule of copper sulphate CuSO₄ dissociate when dissolved in the Cu⁺ positive ions and negative ions SO₄^-. In addition Cu⁺ ions and SO₄^- solution also contains hydrogen (H⁺) and hydroxyl (OH^-) ions of the water. Copper ions Cu⁺ discharged more easily than the hydrogen ions H⁺, therefore at the cathode by passing the current allocation of copper will occur:

Cu⁺⁺+ 2e = Сu.

SO₄^- Ions discharged difficult than the ions OH^-. Therefore, when the current passes from the anode discharge of hydroxyl ions and oxygen is released. SO₄^-ions with H⁺ ions at the anode to form sulfuric acid. The process is different if the anode is made of copper. In this case, the discharge occurs only ions at the cathode. At the opposite anode, metal ions move in a solution. This can be explained by the fact that copper Cu atoms lose electrons easily than OH^- ions, in this case, instead of oxygen evolution will occur at the transition from the anode solution Cu⁺⁺ ions, i.e. Cu – 2e = Cu⁺⁺. Consequently, electrolysis with a copper anode CuSO₄ reduced to copper migration from the anode to the cathode. At the same time the amount of copper sulfate will remain unchanged in the solution