Electrolytic Cell

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About Electrolytic Cell

An electrolytic cell is a device that utilizes electrical energy to decompose some chemical compounds by a process known as Electrolysis. The electrolytic cell is nothing but a special kind of electrochemical cell. Ex: When water undergoes electrolysis, it breaks into hydrogen and oxygen. Here some additional energy is required to overcome the threshold energy barrier.

Voltaic cells are driven by a spontaneous chemical reaction that produces an electric current through an external circuit. These cells are essential because they are the basis for the batteries that fuel modern society. However, they are not the only kind of electrochemical cell. Non-spontaneous reactions usually require electrical energy to operate.

The general form of the reaction can be written as:

Reactants ⇌ Products - Electrical Energy Spontaneous⟶⟵Non-spontaneous (1)

Galvanic Cell and Electrolytic Cell Comparison:

Electrolytic cells are those which work on the chemical energy by utilizing electrical power from the system. The electrolytic cells work on a similar mechanism as that of the Galvanic cells. Both the cells mainly consists of two half cells, such as the oxidation half cell and redox half cell. However, the flow of electrons is a little different. Still, the cathode and anode definition remains the same, where reduction takes place at the cathode and oxidation occurs at the anode. Because both half-reactions' directions have been reversed, the sign, but not the magnitude, of the cell potential has been changed.

Electrolytic cells are very similar to voltaic (galvanic) cells because both require a salt bridge, both have a cathode and anode side, and both have a consistent flow of electrons from the anode to the cathode. However, there are also striking differences between the two cells. The main differences are outlined below:

Difference Between Galvanic Cell and Electrolytic Cell

Galvanic Cell

Electrolytic Cell

Conversion of chemical to electrical energy.

Need external energy source for the reaction.

Cell reaction is spontaneous.

Cell reaction is nonspontaneous.

Electrolytic Cell

Let us take an example to understand clearly about Electrolytic cell. When molten Sodium chloride undergoes decomposition, it gets converted into metallic sodium and Chlorine gas.

2 NaCl -------2 Na+ Cl2

If we put carbon electrodes with both ends c to the molten NaCl in a container, the electrolysis will occur when an additional energy source is applied. Electrons' flow will take place from the anode and neutralize the Na+ ion at the cathode end.

Na++e ------Na

Note that the oxidation site is still the anode and the site of reduction is still the cathode, but the charge on these two electrodes is reversed. The anode is now positively charged and the cathode has a negative charge. The conditions under which the electrolyte cell operates are significant. The substance that is the strongest reducing agent (the substance with the highest standard cell potential value in the table) will undergo oxidation. The substance that is the strongest oxidizing agent will be reduced. If an aqueous sodium chloride solution were used in the above system, hydrogen would undergo reduction instead of sodium because it is a stronger oxidizing agent than sodium.

Electrolytic Cell Application

  • The Electrolytic cells are mainly involved in hydrogen gas and oxygen gas production by water utilization.

  • In the metal extraction process, these are very helpful. Exp - Aluminium extraction from bauxite

  • Electroplating is another feature of the electrolytic cell. This is the process in which a protective covering of a specific metal is done on another metal.

  • Electrowinning is also another application in which metal extraction is done from the raw ore. The leeching phenomenon is generally followed in this process.

  • To remove the impurities from the metal, the electrorefining method is followed.

  • During heavy metals like copper, zinc, and aluminium and the highest purity level, electrolytic cells are used.

Properties of Galvanic and Electrochemical Cells

The galvanic cell converts chemical energy into electrical energy. An electrolytic cell can convert electrical energy to chemical energy. A salt bridge is a connecting link between the two sections that are placed in two different containers. Oxidation reaction takes place at the anode region and the redox reaction in the cathode region. The external cell provides the necessary electrons that enter via cathode and release via anode.

Working Principle of an Electrolytic Cell

Electrochemical cells are devices based on the principle that when a chemical oxidation-reduction reaction occurs, electrons are being transferred from one chemical species to another. In a galvanic cell, the electrons are usually allowed to flow through outside of the device in a circuit to operate some electrical device. In the other type of electrochemical cell, called an electrolytic cell, the reverse process occurs. Electrons in the form of an electric current are deliberately being pumped through the chemicals in the section to force an electric current oxidation-reduction reaction to take place. An example of an electrolytic cell is the setup used to decompose water into hydrogen and oxygen by electrolysis.

FAQ (Frequently Asked Questions)

Q1. What is the Significance of Various Processes that Take Place Inside the Electrochemical Cell?

Ans: The Electrochemical cell generally consists of two conductive sections as Anode and cathode, where the electron movement occurs. An electrode is usually made from any conducting material such as metals, semiconductors or graphite having electron sufficiency.

In a voltaic cell, two metallic electrodes are there dipped in an electrolytic solution. At the anode end, the metal will oxidize from 0 oxidation state to a positive state. The cathode end will accept an electron and get reduced. There must be an external electric connection in both the conductors so that the electrons can move freely. Electrons' continuous flow is nothing but an electric current that generates power to do work.

Q2. What are the Components of an Electrolytic Cell?

Ans: Electrolytic cells generally have three components as Anode, cathode, and electrolyte. Electrolytes are substances that can conduct electricity when dissolved in a polar solution. The Anode is the negatively charged end that has free electrons. The cathode is the positively charged end that has electron deficiency. During Electrolysis, proceed oxidation occurs at the anode end and reduction at the cathode end. Electron movement takes place from anode end to cathode end.