The electrolytic cell it is a medium where energy or an electric current is used to carry out a non-spontaneous oxide-reduction reaction. It consists of two electrodes: the anode and the cathode.
At the anode (+) oxidation occurs, since at this site some elements or compounds lose electrons; while in the cathode (-), the reduction, since in it some elements or compounds gain electrons.
In the electrolytic cell, the decomposition of some substances, previously ionized, occurs through a process known as electrolysis..
The application of the electric current produces an orientation in the movement of the ions in the electrolytic cell. Positively charged ions (cations) migrate towards the charging cathode (-).
Meanwhile, the negatively charged ions (anions) migrate towards the charged anode (+). This charge transfer constitutes an electrical current (top image). In this case, the electric current is conducted by electrolyte solutions, present in the electrolytic cell container..
Faraday's Law of electrolysis states that the amount of substance that undergoes oxidation or reduction at each electrode is directly proportional to the amount of electricity that passes through the cell or cell..
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An electrolytic cell is made up of a container where the material that will undergo the reactions induced by the electric charge is deposited..
The container has a pair of electrodes that are connected to a direct current battery. The electrodes that are usually used are made of an inert material, that is, they do not take part in the reactions.
An ammeter can be connected in series with the battery to measure the intensity of the current flowing through the electrolyte solution. Likewise, a voltmeter is placed in parallel to measure the voltage difference between the pair of electrodes..
Molten sodium chloride is preferred to solid sodium chloride, since the latter does not conduct electricity. Ions vibrate within your crystals, but they are not free to move.
Electrodes made of graphite, an inert material, are connected to the battery terminals. An electrode is connected to the positive terminal of the battery, constituting the anode (+).
Meanwhile, the other electrode is connected to the negative terminal of the battery, constituting the cathode (-). When current flows from the battery, the following is observed:
At the cathode (-) there is a reduction of the Na ion+, which when gaining an electron are transformed into metallic Na:
Na+ + and- => Na (l)
Silvery-white metallic sodium floats on top of molten sodium chloride.
On the contrary, the oxidation of the Cl ion occurs at the anode (+)-, since it loses electrons and becomes chlorine gas (Cltwo), a process that is manifested by the appearance at the anode of a pale green gas. The reaction that occurs at the anode can be outlined as follows:
2Cl- => Cltwo (g) + 2 e-
The formation of metallic Na and Cl gastwo from NaCl it is not a spontaneous process, requiring temperatures higher than 800º C for it to occur. The electric current supplies the energy so that the indicated transformation occurs at the electrodes of the electrolytic cell..
Electrons are consumed at the cathode (-) in the reduction process and are produced at the anode (+) during oxidation. Therefore, electrons flow through the external circuit of the electrolytic cell from anode to cathode..
The direct current battery supplies the energy for the electrons to flow non-spontaneously from the anode (+) to the cathode (-).
The Down cell is an adaptation of the electrolytic cell described and used for the industrial production of metallic Na and chlorine gas..
Down's electrolytic cell has devices that allow the collection, separately, of metallic sodium and chlorine gas. This method of production of metallic sodium is still very practical.
Once released by electrolysis, the liquid metallic sodium is drained, cooled, and cut into blocks. Subsequently, it is stored in an inert medium, since sodium can react explosively on contact with water or atmospheric oxygen..
Chlorine gas is produced in industry, mainly, by the electrolysis of sodium chloride in a less expensive process than the production of metallic sodium.
-In industry, electrolytic cells are used in the electrorefining and electroplating of various non-ferrous metals. Almost all high-purity aluminum, copper, zinc, and lead are produced industrially in electrolytic cells..
-Hydrogen is produced by electrolysis of water. This chemical procedure is also used in obtaining heavy water (DtwoOR).
-Metals like Na, K and Mg are obtained by the electrolysis of molten electrolytes. Also, non-metals like fluorides and chlorides are obtained by electrolysis. Also, compounds like NaOH, KOH, NatwoCO3 and KMnO4 are synthesized by the same procedure.
-The process of coating an inferior metal with a higher quality metal is known as electroplating. The purpose of this is to prevent corrosion of the lower metal and make it more attractive. Electrolytic cells are used in electroplating for this purpose..
-Impure metals can be refined by electrolysis. In the case of copper, very thin sheets of metal are placed on the cathode and large rods of impure copper to be refined on the anode.
-The use of veneered items is common in society. Jewelry and tableware are usually silver plated; gold is electrodeposited on jewelry and electrical contacts. Many objects are covered with copper for decorative purposes.
-The cars have chrome steel fenders and other parts. Chrome plating on a car bumper takes just 3 seconds of chrome plating to produce a 0.0002mm thick shiny surface.
-Rapid electrodeposition of metal produces rough, black surfaces. Slow electrodeposition produces smooth surfaces. The "tin cans" are made of steel coated with tin by electrolysis. Sometimes these cans are chrome plated in a fraction of a second with the thickness of the extremely thin chrome layer.
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