Oxidation-Reduction Reactions

Definition

Oxidation-reduction (redox) reactions are a fundamental class of chemical reactions where the oxidation state of atoms is changed. In these reactions, one substance loses electrons (gets oxidized) while another substance gains electrons (gets reduced), resulting in the transfer of electrons between the reactants.

5 Must Know Facts For Your Next Test

1. Oxidation-reduction reactions are essential in many chemical and biological processes, such as photosynthesis, cellular respiration, and combustion.
2. The driving force behind redox reactions is the tendency of atoms to achieve a more stable electronic configuration by gaining, losing, or sharing electrons.
3. Oxidation and reduction occur simultaneously in a redox reaction, with one substance being oxidized and the other being reduced.
4. The change in oxidation number of the atoms involved is a key indicator of whether a reaction is a redox reaction.
5. Redox reactions can be balanced using the half-reaction method, where the oxidation and reduction half-reactions are identified and then combined.

Review Questions

• Explain the relationship between oxidation and reduction in a redox reaction.
  • In a redox reaction, oxidation and reduction occur simultaneously. One substance is oxidized, meaning it loses electrons and its oxidation number increases, while another substance is reduced, meaning it gains electrons and its oxidation number decreases. The transfer of electrons from the oxidized substance to the reduced substance is the driving force behind the reaction, as both substances strive to achieve a more stable electronic configuration.
• Describe how the concept of oxidation number is used to identify redox reactions.
  • The change in oxidation number of the atoms involved is a key indicator of whether a reaction is a redox reaction. By keeping track of the oxidation numbers of the reactants and products, you can determine which atoms are being oxidized (increasing in oxidation number) and which are being reduced (decreasing in oxidation number). If both oxidation and reduction are occurring, then the reaction is classified as a redox reaction.
• Analyze the role of redox reactions in important chemical and biological processes.
  • Oxidation-reduction reactions are fundamental to many essential chemical and biological processes. In photosynthesis, light energy is used to drive the reduction of carbon dioxide to produce carbohydrates, while the oxidation of water provides the electrons needed. In cellular respiration, the oxidation of organic molecules like glucose provides the energy needed to produce ATP. Combustion reactions, which power many of our technologies, are also redox reactions where a fuel is oxidized by oxygen. Understanding the principles of redox reactions is crucial for comprehending these vital processes.

Related terms

Oxidation: The loss of electrons by a molecule, atom, or ion, resulting in an increase in oxidation state.

Reduction: The gain of electrons by a molecule, atom, or ion, resulting in a decrease in oxidation state.

Oxidation Number: The charge an atom would have if all bonds were ionic, used to keep track of electron transfer in redox reactions.