How Do Electrochemical Reactions Work in Everyday Life?
Reactions are a crucial part of Chemistry. But, what is an electrochemical reaction, and how is it unique? Let us try to discover the answer. Any process either caused or supplemented by the passage of an electric current and engulfing, primarily, the transfer of electrons between two substances – one being liquid and the other being solid - is an electrochemical reaction. The three main components of the reaction are:
The presence of a solution where redox can occur is mandatory. Electrochemical reactions generally take place in water to facilitate the movement of electrons and ions.
The presence of a conductor is compulsory for electrons to get transferred. The conductor is usually some wire so that electrons can move from one site to another.
The ions must be able to move through some form of a salt bridge that facilitates ion migration.
The Process of Electrochemical Reaction
The interactions of matter related to the flow of an electric current depend upon the negatively charged electron characteristics. An electron is a fundamental part of electricity, and hence has an affinity or attraction for positively charged particles of matter, protons. This affinity is synonymous with the chemical affinity that particles exhibit among themselves. All chemical reactions result from the shift in atoms' electron structure, wherein free electrons can combine with particles of matter (reduction) or get released by them (oxidation). The substances that take part in the electrochemical process are called electrolytes or ionic conductors. Electrons are available in considerable quantities in a relatively mobile state only in substances called electronic conductors, among which metals are most crucial. Thus, an electronic conductor must be present as the primary component of any system in which electrochemical reactions occur.
Moreover, the availability of electrons in a conductor is limited by energy distribution to such a degree that electrochemical reactions only occur near the electronic conductor's surface. Hence, electrochemical reactions typically happen at the common boundary between an electronic conductor, that is, an electrode, and an ionic conductor of electricity - an electrolytic solution. It is important to note that electrochemical processes will take place only to the degree that electricity can pass through such a system as a whole. As such, the system must form a closed loop. In a nutshell, if at one metal-solution interface, electrons are coming out of the metal, thereby reducing a component of the solution, there has to be a second-metal solution interface wherein electrons are going inside the metal in the process of oxidation. The two electrodes and ionic conductor in between represent an electrochemical cell. Let us try and analyze the concept of a cell in detail.
Application of Electrochemical Cell
An electrochemical cell is a tool that can create energy from the chemical reactions happening within it or utilize the electrical energy supplied to it to facilitate chemical reactions in it. A typical example of an electrochemical cell is a standard 1.5-volt cell used to power many electrical appliances such as TV, remotes, etc. The main applications of an electrochemical cell are –
The use of electrolytic cells is common in the electro-refining of non-ferrous metals.
The production of high-purity zinc, aluminium, and copper involves the use of electrolytic cells.
They are also used in the electro-winning of non-ferrous metals.
It is possible to extract metallic sodium from molten sodium chloride by placing the latter in an electrolytic cell with an electric current.
Example of an Electrochemical Reaction
An electrochemical reaction is a spontaneous reaction used to generate an electric current in an electrochemical cell. An example of an electrochemical reaction is when gaseous oxygen and hydrogen combine in a fuel cell to create water and energy, typically a combination of heat and electrical energy. An electrochemical cell can be represented as – Zn/Zn2+ || Cu2+ /Cu
Electrochemistry Applications
Electrochemistry is that branch of physical chemistry that engages with the interconversion of chemical energy and electrical energy. Electrochemistry is a salient part of the broader discipline of Chemistry. It is concerned with the relationship between electrical potential, a measurable and quantitative phenomenon, and identifiable chemical change, with either electrical potential as an outcome of a particular chemical change or vice-versa. There are numerous electrochemistry applications. We have mentioned some of them below –
An electrochemical reaction is a driving force behind batteries as they are made of one or more galvanic cells or fuel cells. We use batteries in all spheres of life, and hence their utility.
An electrolytic cell for electroplates. Electroplating has applications such as corrosion protection of certain metals, jewellery production, etc.
Electrochemistry is necessary for several industries like the chlor alkali industry.
Conclusion
Electrochemistry is a fascinating discipline. It is necessary to learn about electrochemical reactions because they have immense academic as well as practical value. Understanding the responses enables us to understand the functioning of mundane things like a battery or cell.
FAQs on What Is an Electrochemical Reaction?
1. What is an electrochemical reaction?
An electrochemical reaction is a process that involves the conversion between chemical energy and electrical energy. These reactions are driven by the transfer of electrons and are categorised as redox (reduction-oxidation) reactions. They take place within an electrochemical cell, where chemical changes either produce an electric current (in a galvanic cell) or are caused by one (in an electrolytic cell).
2. What are the key components of an electrochemical cell?
An electrochemical cell consists of four main components that work together to facilitate the reaction:
- Anode: The electrode where oxidation (loss of electrons) occurs. It is considered the negative electrode in a galvanic cell.
- Cathode: The electrode where reduction (gain of electrons) occurs. It is the positive electrode in a galvanic cell.
- Electrolyte: An ion-conducting solution that contains the ions of the species involved in the reaction.
- Salt Bridge or Porous Barrier: A device that connects the two half-cells, allowing ion flow to maintain electrical neutrality without letting the solutions mix.
3. What are the two main types of electrochemical cells?
The two primary types of electrochemical cells are distinguished by their energy conversion process:
- Galvanic Cell (or Voltaic Cell): This type of cell converts chemical energy into electrical energy through a spontaneous redox reaction. Common batteries are examples of galvanic cells.
- Electrolytic Cell: This cell uses electrical energy to drive a non-spontaneous redox reaction. It converts electrical energy into chemical energy, a process known as electrolysis, used in metal plating and refining.
4. What is the fundamental difference in how energy is used in a galvanic versus an electrolytic cell?
The fundamental difference lies in spontaneity and energy flow. A galvanic cell harnesses a naturally occurring, spontaneous chemical reaction to produce electrical energy. In contrast, an electrolytic cell requires an external source of electrical energy to force a non-spontaneous chemical reaction to occur. Essentially, one generates electricity from chemistry, while the other uses electricity to perform chemistry.
5. What are some common examples of electrochemical reactions in daily life?
Electrochemical reactions are central to many technologies. Common examples include:
- Batteries: Dry cells, lead-acid car batteries, and lithium-ion batteries in phones all operate on the principles of galvanic cells.
- Corrosion: The rusting of iron is a natural, undesirable electrochemical process.
- Electroplating: Coating a cheaper metal with a more expensive one, like silver or chromium, uses an electrolytic cell.
- Metabolism: Biological processes, like cellular respiration, involve electron transfer chains that are fundamentally electrochemical.
6. What is the importance of the electrochemical series in predicting reactions?
The electrochemical series (or activity series) is a list of elements ranked according to their standard electrode potentials (E°). Its primary importance is in predicting the spontaneity of a redox reaction. By comparing the E° values of two half-reactions, we can determine which species will be oxidised (the one with the lower E°) and which will be reduced (the one with the higher E°), and thus calculate the overall cell potential to confirm if the reaction will proceed spontaneously.
7. Why is a salt bridge essential for a galvanic cell to function?
A salt bridge is crucial because it maintains electrical neutrality in the two half-cells. As electrons flow from the anode to the cathode, a build-up of positive charge occurs in the anode compartment and negative charge in the cathode compartment. The salt bridge allows ions (e.g., K⁺ and Cl⁻) to migrate into the half-cells to neutralise this charge build-up. Without it, the charge imbalance would quickly stop the flow of electrons, and the reaction would cease.
8. How does the Nernst equation explain the effect of reactant concentration on cell potential?
The standard electrode potential is calculated under standard conditions (1 M concentration, 1 atm pressure, 298 K). The Nernst equation allows us to calculate the cell potential under non-standard conditions. It shows that the cell potential (E_cell) is dependent on the reaction quotient (Q), which is the ratio of the concentrations of products to reactants. Therefore, changing the concentration of reactants or products directly alters the cell's EMF, a principle vital for understanding how a battery's voltage drops as it is used up.
9. What is the relationship between Gibbs Free Energy (ΔG) and the EMF of an electrochemical cell?
The relationship is given by the equation ΔG = -nFE_cell, where 'n' is the number of moles of electrons transferred, 'F' is the Faraday constant, and 'E_cell' is the cell potential. This equation directly links thermodynamics with electrochemistry. A positive E_cell results in a negative ΔG, which signifies a spontaneous reaction (characteristic of a galvanic cell). Conversely, a negative E_cell gives a positive ΔG, indicating a non-spontaneous reaction that requires energy input (as in an electrolytic cell).
