Electrochemical Cell Reactions

The term “oxidation” refers to the loss of electrons from the surfaces of an atom, ion, or molecule in an electrochemical reaction, which is defined as follows: The polar opposite of oxidation is reduction, which is defined as the recovery of electrons that have been lost. In these reactions, the oxidation numbers alter in accordance with the situation. A balanced half-reaction can serve as an illustration of this. This reaction is nonspontaneous, meaning that electricity is required to allow the reaction to take place, as opposed to a spontaneous reaction, which creates electricity on its own.

In this section, you will find an example of an experiment with NaCl, a molten salt of sodium chloride. SALT dissociates into its ions when melted, producing Na+ (cation) and Cl- (anion) .

The reaction that occurs as a result is: Na+ + e- —> Na

The anode is the other electrode that provides electrons to the cathode. There is no doubt about oxidation in this case, and the half equation is as follows: The reaction 2Cl -> Cl2 + 2e-

When aqueous solutions are employed in the experiment, it becomes clear that there are other processes occurring. The most straightforward redox reaction for this is as follows:

At the cathode, the reaction is 2H2O + 2e- -> H2 + 2OH-  (Water is reduced.)

At the anode, 2H2O -> 4H+ + O2 + 4e-  is produced (Water is oxidized.)

Electrochemical cell

An electrochemical cell is a device that may either generate electrical energy from the chemical reactions that take place inside it, or use the electrical energy that is supplied to it to facilitate chemical reactions that take place inside it. Essentially, these devices have the capability of transforming chemical energy into electrical energy or the other way around. For example, a normal 1.5-volt cell, which is used to power numerous electrical equipment such as television remotes and clocks, is a popular example of an electrochemical cell.

Galvanic cells and Voltaic cells are two terms used to describe cells that are capable of generating an electric current as a result of chemical events occurring within them. Electrolytic cells, on the other hand, are those cells that, when an electric current is delivered through them, induce chemical reactions to occur within them.

Type of electrochemical cell

Voltaic Cells

Voltaic cells are devices that generate electric current from the energy released by a spontaneous redox reaction in two half-cells. Electrochemical cells are composed of two conductive electrodes, which are referred to as the anode and the cathode, respectively. The electrode where oxidation takes place is the anode. The reduction takes place at the cathode electrode . Electrodes can be constructed from any material that is suitably conductive, including metals, semiconductors, graphite, and even conductive polymers, among other materials. It is the electrolyte that sits in the space between these electrodes, and it contains ions that can freely flow about.

During the production of the voltaic cell, two distinct metal electrodes are used, each immersed in an electrolyte solution. The anode will be subjected to oxidation, while the cathode will be subjected to reduction. During the process of oxidation, the anode metal will transition from an oxidation state of 0 (in solid form) to a positive-oxidation state, and it will eventually become an ion. When the metal ion in the solution comes into contact with the cathode, it will accept one or more electrons from the cathode, and the ion’s oxidation state will be reduced to zero. This results in the formation of a solid metal that deposits on the cathode. Electricity must be established between the two electrodes in order to allow for the passage of electrons that leave the metal of the anode and flow via the connection to the ions on the surface of the cathode. Electrical connection It is possible to employ this flow of electrons to create an electrical current that can be used to do work, such as turning a motor or lighting a lamp.

Electrolytic Cells

Electrolysis is a method of inducing a chemical reaction that takes place in an electrolytic cell. Electrical energy is used to do this. Using an electric current to run through an ionic substance that is either molten or completely dissolved, chemical reactions occur at the electrodes and materials are separated. Electrolysis is a technique used to separate materials from one another.

Electrolysis can be conceived of as the operation of a non-spontaneous galvanic cell in some cases. The reaction may or may not be spontaneous, depending on how readily elements give up electrons (oxidation) and how energetically beneficial it is for elements to accept electrons (reduction). By externally supplying the energy required to overcome the energy barrier to spontaneous reaction, the desired reaction is “allowed” to proceed under particular conditions, hence increasing its chances of success.

The following are the primary components necessary for electrolysis:

The following are the primary components necessary for electrolysis:

An electrolyte is a material that contains free ions that are capable of carrying electrical currents. If the ions are not mobile, as they are in a solid salt, electrolysis will not be possible.

A direct current (DC) supply: provides the energy required to produce or discharge the ions in the electrolyte by supplying them with direct current. Electrons are responsible for the transmission of electric current in the external circuit.

Electrodes consist of two parts: an electrical conductor that serves as a physical interface between the electrical circuit that supplies the energy and the electrolyte; and an electrolyte.

Voltaic cell reaction

The voltaic cell operates on the premise of a simultaneous oxidation and reduction reaction, known as a redox reaction. This redox reaction consists of two half-reactions that are mutually exclusive. Typical voltaic cell redox pairs are copper and zinc, which are represented in the half-cell reactions as follows: 

Zinc electrode (anode): Zn(s) → Zn2+(aq) + 2 e–

Using copper as an electrode (cathode), the equation is Cu2+(aq) + 2 e– → Cu (s)

Separate beakers are used to construct the individual cells. The metal electrodes are immersed in electrolyte solutions to provide a current path. A salt bridge connects each half-cell to the other, allowing for the free transport of ionic species between the two cells When the circuit is complete, the current flows and the cell “produces” electrical energy.

Copper quickly oxidised zinc; the anode is zinc and the cathode is copper. The anions in the solutions are sulphates of the corresponding metals. When an electrically conducting device is used to link the electrodes, the electrochemical reaction occurs as follows: Zn + Cu2+ Zn2+ + Cu

With each electron produced by the oxidation of the zinc electrode, two electrons are transferred through the wire to the copper cathode (Zn2+ + 2e-), (Cu2++ 2e-). Cu is formed when the electrons are located Cu2+ in solution, resulting in the reduction of copper to copper metal. It will be necessary to employ the zinc electrode during the reaction, and the metal will contract in size, whilst the copper electrode will expand in size due to the deposition of Cu that is being created. It is vital to have a salt bridge in order for the charge to continue to flow through the cell. A salt bridge is required because, without one, the electrons produced at the anode would accumulate at the cathode, causing the reaction to cease.

A common application for photovoltaic cells is as a source of electrical power. They are designed to generate direct current by their very nature. A battery is made up of a collection of voltaic cells that are connected in series. When it comes to batteries, the anodes (which are made of lead) and cathodes (which are made of lead dioxide) are the most important components.

Conclusion

In an electrochemical reaction, electrons are transferred between a solid electrode and a material, such as an electrolyte, through a conductor of electricity. This flow causes an electric current to pass across the electrodes, allowing the reaction to either liberate or absorb heat depending on the situation. There is a rule that governs the reactions that occur at each electrode, and this rule may be found here. Whenever an active metal cation is used in the cathode, water is reduced in the cathode. When the anion is a polyatomic ion, water is oxidised in the anode, resulting in the reduction of water. Sulphates and nitrates are two examples of anions.