Gibbs Free Energy Calculator

Calculate Reaction Spontaneity and Equilibrium

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Gibbs Energy from ΔH and ΔS

Calculate Gibbs free energy change using enthalpy change and entropy change.

ΔG: - kJ/mol
Reaction is: -

Equilibrium Constant Calculator

Calculate equilibrium constant from standard Gibbs free energy change.

K: -

Reaction Quotient Calculator

Calculate actual Gibbs energy using standard Gibbs energy and reaction quotient.

Actual ΔG: - kJ/mol

Understanding Gibbs Free Energy

What is Gibbs Free Energy?

Gibbs free energy (G) is a thermodynamic potential that measures the maximum reversible work that may be performed by a thermodynamic system at constant temperature and pressure. Key points:

  • ΔG = ΔH - TΔS
  • Measures reaction spontaneity
  • Indicates direction of change
  • Determines equilibrium position

Spontaneity Criteria

Understanding ΔG values:

  • ΔG < 0: Spontaneous reaction
  • ΔG = 0: At equilibrium
  • ΔG > 0: Non-spontaneous reaction
  • Standard conditions: 1 atm, 25°C

Relationship with Equilibrium

Key relationships:

  • ΔG° = -RT ln(K)
  • ΔG = ΔG° + RT ln(Q)
  • At equilibrium: Q = K
  • Temperature affects equilibrium

Applications

Gibbs energy is used in:

  • Chemical equilibrium
  • Phase transitions
  • Electrochemistry
  • Biochemical processes
  • Materials science
  • Industrial chemistry

Advanced Concepts

Related thermodynamic concepts:

  • Chemical potential
  • Phase equilibria
  • Coupled reactions
  • Non-ideal solutions
  • Electrochemical cells

Essential Gibbs Free Energy Formulas

Basic Equation

ΔG = ΔH - TΔS

Equilibrium Relationship

ΔG° = -RT ln(K)

Non-Standard Conditions

ΔG = ΔG° + RT ln(Q)