What units should I use for enthalpy (ΔH) and entropy (ΔS)?

Enthalpy (ΔH) must be entered in kilojoules per mole (kJ/mol), while entropy (ΔS) must be entered in joules per mole-Kelvin (J/mol·K). The calculator automatically handles the unit conversion factor of 1000.

How does the calculator determine if a reaction is spontaneous?

A reaction is spontaneous if the calculated Gibbs free energy change (ΔG) is negative, and non-spontaneous if ΔG is positive.

What does the equilibrium temperature mode calculate?

It calculates the temperature at which ΔG equals zero, representing the point where the system is at equilibrium and the reaction direction can shift.

Can I input temperatures in Celsius?

Yes, you can select Celsius as the temperature unit, and the calculator will automatically convert it to Kelvin for the thermodynamic equations.

How is the equilibrium constant K calculated?

The calculator estimates K using the relationship ΔG = -RT ln(K), where R is the universal gas constant and T is the temperature in Kelvin.

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Thermodynamics (Gibbs Free Energy) Calculator

Calculate Gibbs free energy ΔG = ΔH − TΔS, reaction spontaneity, equilibrium temperature, and equilibrium constant K.

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Spontaneity of methanol combustion at 25 °C

ΔH = -726.4 kJ/mol, ΔS = -0.181 kJ/mol·K at 298 K → strongly spontaneous.

{"result":"ΔG = -672.435 kJ/mol → spontaneous at 298.15 K; K = very large (≫ 1).","metadata":{"result":{"dG":-672.435,"spontaneous":true}}}

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SettingsAdjust formats, ranges, numbers, and modes.6

Calculation ModeselectOptionalEnthalpy ΔH (kJ/mol)numberOptionalNegative = exothermic, positive = endothermic.Entropy ΔS (J/mol·K)numberOptionalNegative = more ordered, positive = more disordered. Units are J (not kJ).Temperature (K)numberOptionalAbsolute temperature. Used in 'Find ΔG' mode.Temperature UnitselectOptionalDecimal PlacesnumberOptional

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Thermodynamics (Gibbs Free Energy) Calculator

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1. Spontaneity of Methanol Combustion

2. Finding the Equilibrium Temperature for Calcium Carbonate Decomposition

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