Calculate spontaneity, equilibrium constants, and temperature crossover for any chemical reaction.
Enter standard enthalpy (ΔH°), entropy (ΔS°), temperature, and optionally the reaction quotient Q to get a complete thermodynamic picture — spontaneity verdict, equilibrium constant K, and the exact temperature crossover point.
Quick guide for the three most common use cases.
Standard Conditions: Enter ΔH°, ΔS°, and T (usually 298 K). Leave Q blank. Returns ΔG° and the spontaneity verdict under standard conditions.
Non-Standard Conditions: Enter Q (ratio of product to reactant concentrations). Returns the actual ΔG and predicts which direction the reaction proceeds.
Temperature Crossover: For reactions where ΔH and ΔS have the same sign, the calculator shows the exact temperature where the reaction switches between spontaneous and non-spontaneous.