Calculation Hub

Equilibrium Calculator

Calculate chemical equilibrium constants, reaction quotients, and equilibrium concentrations. Analyze shifts in equilibria according to Le Chatelier's principle.

About Equilibrium Calculator

Historical Development

Chemical equilibrium was first conceptualized by Claude Louis Berthollet around 1803 after observing salt formations at Lake Natron. The mathematical foundation was later established by Cato Maximilian Guldberg and Peter Waage in 1864 through their law of mass action, revolutionizing our understanding of reversible reactions.

Mathematical Foundation

For reaction: aA + bB ⇌ cC + dD
Keq = [C]ᶜ[D]ᵈ / [A]ᵃ[B]ᵇ
ΔG° = -RT ln(Keq)
ln(K₂/K₁) = -(ΔH°/R)(1/T₂ - 1/T₁)

  • Keq = Equilibrium constant
  • [ ] = Concentration in mol/L
  • a,b,c,d = Stoichiometric coefficients
  • ΔG° = Standard Gibbs energy
  • ΔH° = Standard enthalpy change

Types of Equilibria

Homogeneous Equilibria:

  • All species in same phase
  • Gas phase reactions
  • Solution reactions
  • Kc notation used

Heterogeneous Equilibria:

  • Multiple phases present
  • Solids excluded from Keq
  • Phase boundaries important
  • Surface area effects

Le Châtelier's Principle

Concentration Changes:

  • Adding reactant shifts right
  • Adding product shifts left
  • Removal shifts to compensate
  • Keq remains constant

Physical Changes:

  • Temperature affects Keq
  • Pressure affects gas equilibria
  • Volume changes shift position
  • Catalyst speeds equilibration

Applications

Industrial Processes:

  • Haber process (NH₃)
  • Contact process (H₂SO₄)
  • Ostwald process (HNO₃)
  • Yield optimization

Biological Systems:

  • Buffer solutions
  • Oxygen transport
  • Enzyme reactions
  • Membrane potentials

Practical Considerations

Reaction Control:

  • Temperature optimization
  • Pressure adjustment
  • Concentration control
  • Catalyst selection

Analysis Methods:

  • Spectroscopy
  • pH measurements
  • Conductivity
  • Pressure monitoring