A galvanic cell is an electrochemical cell that generates an electric current by transferring electrons in redox reactions. This cell is powered by a spontaneous chemical reaction that generates an electric current via an external circuit. Galvanic cell reactions generate energy, which is then used to do work. Furthermore, a redox reaction is a reaction that involves the transfer of electrons between chemical species (the atoms, ions, or molecules involved in the reaction).
A galvanic cell is made up of at least two half cells, one reduction cell, and one oxidation cell. The energy for galvanic cell operations is provided by chemical reactions in the two half cells. Many galvanic cells are commercially significant. Dry cells, mercury cells, rechargeable Ni-Cd batteries, fuel cells, and lead storage cells are examples of these. The Daniell cell is a type of galvanic cell.
A Daniell cell is the best example of a galvanic cell that converts chemical energy into electrical energy. The Daniell cell consists of two electrodes of dissimilar metals, Zn and Cu; each electrode is in contact with a solution of its own ion; Zinc sulfate and copper sulfate respectively.
Galvanic cells should not be confused with electrolytic cells as they generate energy from spontaneous redox reactions, whereas electrolytic cells use non-spontaneous reactions and thus need an external electron source, such as a DC battery or an AC power source. A battery (storage cell) is a galvanic cell (or series of galvanic cells) containing all of the reactants required to generate electricity. A fuel cell is also a galvanic cell that requires a constant external supply of one or more reactants in order to generate electricity.
Galvanic cells are also useful for corrosion prevention. A galvanic cell can be made from any two metals. When two metals come into contact, one can act as an anode and the other as a cathode, resulting in galvanic corrosion of the more anodic metal. In a conducting electrolyte, two metals with different potentials result in galvanic corrosion of the more anodic metal. The relative position of metal on the galvanic series usually determines whether it will act as an anode or a cathode in combination with another metal in the same environment.
Each half-cell contains an electrode in an electrolyte. The separation is necessary to prevent direct chemical contact of the oxidation and reduction reactions, creating a potential difference. The electrolyte is an aqueous or molten substance that conducts electricity. All solutions in a galvanic cell are electrolytes, including the solutions in which the electrodes are immersed and the solution that forms the salt bridge. Electrons always flow from the anode to the cathode or from the oxidation half cell to the reduction half cell.
A salt bridge refers to a device used to form an electrochemical cell by providing a means to support the free flow of ions between the oxidation and reduction of half-cell components. A salt bridge facilitates corrosion because corrosive reactions typically occur in the presence of electrochemical cells.
Table of Contents
Summary
- A galvanic cell is an electrochemical cell that converts the free energy of a chemical process into electrical energy.
- A galvanic cell is made up of two half cells i.e., anodic and cathodic. The cell reaction is of the redox kind. Oxidation takes place at the anode and reduction at the cathode.
- Electrons always flow from the anode to the cathode or from the oxidation half cell to the reduction half cell.
Frequently Asked Questions
1. What is cathode definition?
The cathode is the electrode of an electrochemical cell where reduction takes place. In layman’s terms, the cathode is an electrolytic cell’s negative terminal.
2. What is a cathode ray tube?
A cathode-ray tube is a type of vacuum tube that produces pictures when an electron beam impacts a phosphorescent surface. Cathode ray tubes are used in the majority of desktop computer screens. A computer display’s CRT is analogous to a television receiver’s “picture tube”.
3. What is Daniell Cell?
A Daniell cell is a form of a galvanic cell that transfers chemical energy to electrical energy. The cell is made up of zinc and copper electrodes, with zinc functioning as the anode and copper acting as the cathode. Electrons always move from the anode to the cathode or from the oxidation half cell to the reduction half cell. The Daniell Cell has a voltage of 1.1 volts.
4. Is helium a gas?
Helium (He) is an inert gas and chemical element in Periodic Group 18. (noble gases). Helium, the second lightest element (only hydrogen is lighter), is a colorless, odorless, and tasteless gas that freezes at 268.9 degrees Celsius (452 degrees Fahrenheit).
5. At what temperature does water freeze?
Water’s normal freezing and melting points are 0 degrees Celsius or 32 degrees Fahrenheit.
6. Hydrogen cyanide polar or nonpolar?
HCN is a polar molecule.
As can be seen from the HCN lewis structure, the electronegativity difference between nitrogen (3.04) and hydrogen (2.2) makes it a polar molecule.
7. What is the melting point of water?
The melting point of pure water ice at 1 atmosphere of pressure is very close to 0 °C, which is 32 °F or 273.15 K.
8. What is the surface tension of water?
Surface tension refers to the ability of a liquid’s surface to resist an external force because of its molecules’ cohesion. At 20 °C (68 °F), the surface tension of water is 0.07275 joules per square meter.
9. Is MgCl2 Ionic or Covalent?
When the magnesium atom loses two electrons to create the Mg2+ ion and each chlorine receives one electron to form the Cl– ion, an ionic connection is formed between the magnesium and chlorine atoms.
Check “Is MgCl2 ionic or covalent?”.
10. What is the hydrogen phosphate formula?
The hydrogen phosphate formula is [HPO4]2-. The molar mass of this compound is 95.97 g/mol. The ion is formed by the loss of two protons H+ from phosphoric acid H3PO4, which accounts for the ion’s charge of 2.
11. What is a hydrogen ion?
The nucleus of a hydrogen atom separated from its electron is known as a hydrogen ion. The hydrogen nucleus is made up of a proton, which is a particle with a unit positive electric charge.
12. Is hydrogen sulfide poisonous?
Hydrogen sulfide (H2S) is made up of a single sulfur atom bonded to two hydrogen atoms. It is a highly poisonous, flammable gas with the odor of rotten eggs that are frequently produced by bacterial decomposition of organic matter in the absence of oxygen.
13. What is the electronegativity value of hydrogen?
The electronegativity of hydrogen is 2.2.
Electronegativity is used to determine whether an ionic or covalent connection will form between two atoms. It can also determine whether the molecule is polar or nonpolar.
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