Expository Essay Sample on Cells in Chemistry
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Introduction
Batteries are commonly referred to as cells in chemistry, precisely chemical cells. Chemistry is the foundation upon which batteries thrive. A battery composes of one or more galvanic cells used to store and produce chemical energy using chemicals. A galvanic cell is composed of at least two half cells. Which are oxidation and reduction cells. The chemical reactions in the reduction and oxidation cells produce the energy that ensures the battery is functional.
Each of these halves consists of electrode and electrolyte solution which contains ions that have been derived from the electrode by reduction or oxidation reactions.
The Voltaic cells are run by chemical reactions that are spontaneous in nature producing electrical energy through an outside circuit. The cells are important since they are what fuel modern society. The reverse reaction has a nonspontaneous nature and therefore occur with the help of electrical energy
Spontaneous and Non-spontaneous Reaction
There is a possibility of the construction of a cell that does not rely on the chemical system and which means driving electrical current through the system. These types of cells are called electrolytic cells which operate in a means we call electrolysis. Electrolysis is established by driving a redox reaction in a direction that the reaction lacks spontaneity by channeling an electrical current through the system while working on the chemical system itself making it non-spontaneous.
Just like galvanic cells, electrolytic cells also have two half cells one being the reduction half while the other being the oxidation half-cell. The two cells differ in the sense that there is the likelihood of reversal from the direction of spontaneous electron flow in a galvanic cell, but the concept of defining anode and cathode remains constant, reduction occurs at the cathode while oxidation occurs in the anode.
The galvanic (voltaic) and electrolytic cells are similar because they both require a salt bridge, they both have the cathode and anode section. There are differences in the cells the differences areas are listed below:
| Galvanic Cell | Electrolytic Cell |
| Converts chemical energy into electrical energy | Converts electrical energy to chemical energy |
| The spontaneous redox reaction is spontaneous and results in electrical energy | The reaction is a nonspontaneous redox reaction and electrical energy has to be supplied to start the reaction |
| The two half cells are located in different containers with a salt bridge interlinking them | The two half cells are in the same container with molten electrolyte in place |
| The cathode is positive and the anode is negative. The reaction at the cathode is the reduction and at the anode is oxidation | The cathode is negative and the anode is positive. The reaction at the cathode is the reduction and at the anode is oxidation |
| Electrons are supplied by the species being oxidized and they migrate from anode to cathode in the external circuit | The electrons are supplied by the external battery where they enter through the cathode and exit via the anode |
| The salt bridge connects the separate solutions allowing free movement of electrons | A voltmeter is a device used to measure the flow of electric currents between the half-two reactions and it does so in volts |
Reference
Battery and Energy Technologies. (n.d.). Retrieved March 31, 2017, from http://www.mpoweruk.com/chemistries.htm
Chemistry of Batteries. (n.d.). Retrieved March 31, 2017, from http://www.science.uwaterloo.ca/~cchieh/cact/c123/battery.html
L. (2016, July 21). Electrochemical Cells. Retrieved March 31, 2017, from https://chem.libretexts.org/Core/Analytical_Chemistry/Electrochemistry/Basics_of_Electrochemistry/Electrochemical_Cells
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