The electrolysis is a process by which one can separate the elements having a compound using electricity . Some substances such as salts and some metal oxides are good conductors of electricity and suffer decomposition when they experience the passage of an electric current , these substances are called electrolytes , and this phenomenon is known by the name of electrolysis. It is a process of oxidation and reductionThey involve an increase in the free energy of the system that requires an external force of energy. The reactions that occur in the electrolysis process are determined by energy laws .
What is electrolysis?
Electrolysis is the process by which electric current passes through a substance to effect a chemical change in it, producing separation . The chemical change is one in which the substance loses or gains an electron and can be oxidation or reduction .
- History of electrolysis
- What is it for
- How does it work
- Electrolysis of water
- Electrolysis of sodium chloride
History of electrolysis
It was the British William Whewell , a great scientist, philosopher and author of numerous texts, who together with Michael Faraday in 1834 invented the term “electrolysis” to define the process of chemical decomposition of galvanic current . At the beginning of the 19th century, this word was rapidly introduced in the fields of chemistry, mineralogy and metallurgy through a series of experiments in which, when introducing electricity into a substance, different types of decompositions could arise , allowing to know and understand the elementsof said substance. In 1850 and 1860 medical experiments were done in North America and Europe using electrolysis.
What is it for
Electro metallurgy : many of the metals that are highly reactive, such as those belonging to group 1 and 2, are extracted from their matrices by electrolysis of their molten minerals. Metals such as sodium and magnesium are manufactured by the electrolysis of their molten chlorides . Pure aluminum is obtained from a solution of its oxide in molten cryolite and is used in the manufacture of some important substances such as hydrogen, chlorine, sodium hydroxide and oxygen. It is used in the production of aluminum, lithium, sodium, hydrochloric acid, potassium chloride, potassium hydrogen, and magnesium. It is used in saline solutionsfor the production of chlorine which is used in swimming pool water. Through electrolysis anodization , metals in a state of corrosion can be protected .
How does it work
The electrical conductivity of substances is a displacement of electrical charge through them. This displacement that occurs in charges can occur in two ways: by means of a flow of electrons , as usually happens in metals, and which are given the name of first-class conductors; and by means of movement of the positive and negative ions , by means of a solution or a fluid ionic compound. This form of conductivity is known as ionic conductivity , also called electrolytic, in the case of the conductivity of electrolytes that are conductors of the second kind. It is then, a process in which the step of theElectric current through a solution or a molten electrolyte results in an oxidation -reduction reaction , better known as redox.
We can understand the process by looking at an example that involves the purification of a copper metal. This process will require an anode , a positively charged electrode, and a cathode , a negatively charged electrode. In this case, an impure copper metal is the anode, while the pure copper metal is the cathode.
Through the electrolysis process, different compounds can be decomposed into their elements, such as hydrogen . It is also used to purify a metal such as copper. It is also used to coat some metals with another metal in order to beautify it or prevent corrosion. The metals that are usually deposited are gold, silver, chromium, tin and this process is called electroplating .
Electrolysis of water
The electrolysis of water needs to ensure that the water is not in its pure state , it must have some concentrations of salts and some minerals ; and direct current must be used during the process. It allows to obtain chemical elements , such as hydrogen and oxygen. It can be applied to fresh or salt water, obtaining different results. From salt water we will obtain chlorine and hydrogen in a gaseous state.
Electrolysis of sodium chloride
The chloride ions lose their electrons when transformed into atoms chlorine , which in turn form the molecules of gaseous chlorine . The anodic reaction that occurs in this case is oxidation. These electrode reactions are called half-reactions , and the overall reaction for the electrolysis of sodium chloride is: 2Na + + 2Cl- → 2Na ° + Cl2.