Standard Reaction Potentials and Free-Energy Change

This article discusses the standard reaction potentials and free-energy change in biochemistry. It explains how the flow of electrons can make energy available, and how the free-energy change of a redox reaction can be calculated. An example is given of the free-energy change for the reaction of acetaldehyde with NADH to form ethanol and NAD+.

Questions

• What is a standard reaction potential?
• What is free-energy change?
• How do you calculate the free-energy change of a redox reaction?
• What is an example of a redox reaction?

Answers

• A standard reaction potential is the potential difference between the oxidized and reduced forms of a redox couple under standard conditions.
• Free-energy change is a measure of the amount of energy available to do work in a chemical reaction.
• The free-energy change of a redox reaction can be calculated using the equation ∆G = -nFE∆E, where n is the number of electrons transferred, F is the Faraday constant, and ∆E is the standard reaction potential.
• An example of a redox reaction is the reaction of acetaldehyde with NADH to form ethanol and NAD+. The standard reaction potential for this reaction is 0.123 V, and the free-energy change is -23.7 kJ/mol.