Can someone explain the difference between delta G naught, delta G naught prime, and delta G

Can someone explain the difference between delta G naught, delta G naught prime, and delta G? what does the value tell us about the reaction? please explain in detail. Thank you!

The Correct Answer and Explanation is:

ΔG°, ΔG°′, and ΔG: Understanding the Differences and Their Significance

In thermodynamics and biochemistry, Gibbs free energy changes are used to predict the spontaneity and direction of chemical reactions. Three related but distinct terms are commonly used: ΔG°, ΔG°′, and ΔG.

ΔG° (Standard Gibbs Free Energy Change)

ΔG° represents the change in free energy for a chemical reaction under standard conditions, which are:

• 1 atm pressure for gases,
• 1 M concentration for all solutes,
• 298 K (25°C) temperature.

This value is a fixed constant for a given reaction and indicates the energy change when reactants and products are in their standard states. If ΔG° is negative, the reaction is spontaneous under standard conditions. If it is positive, the reaction is nonspontaneous under those same conditions.

ΔG°′ (Standard Gibbs Free Energy Change at pH 7)

ΔG°′ is a modified standard Gibbs free energy used specifically in biochemistry. It is the free energy change under standard conditions except that the pH is fixed at 7.0, rather than assuming 1 M [H⁺] as in ΔG°. This reflects biological reality, where most cellular reactions occur near neutral pH.

Thus, ΔG°′ is used to compare biochemical reactions more accurately, especially those involving protons (H⁺), since physiological conditions deviate from standard chemical conditions.

ΔG (Actual Gibbs Free Energy Change)

ΔG refers to the actual free energy change under non-standard conditions—the real concentrations of reactants and products at a given moment. It is calculated using the equation: ΔG=ΔG∘+RTln⁡Q\Delta G = \Delta G^\circ + RT \ln QΔG=ΔG∘+RTlnQ

Where:

• R is the gas constant (8.314 J/mol·K),
• T is temperature in Kelvin,
• Q is the reaction quotient.

Interpreting the Values

• If ΔG < 0, the reaction proceeds spontaneously forward.
• If ΔG = 0, the reaction is at equilibrium.
• If ΔG > 0, the reaction is nonspontaneous and proceeds in reverse.

Understanding these differences helps predict and control biochemical reactions, both in laboratory and physiological conditions.