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Gibbs Free Energy Calculator

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The Gibbs Free Energy Calculator is a tool designed to simplify the process of calculating the change in Gibbs Free Energy (ΔG) for chemical reactions or physical processes. This calculator is incredibly useful for students, chemists, and engineers who are dealing with thermodynamics and need a quick way to determine the feasibility of reactions under constant temperature and pressure.

Purpose and Functionality

Gibbs Free Energy is a thermodynamic quantity that represents the maximum amount of work that a thermodynamic system can perform at a constant temperature and pressure. It is a critical factor in predicting the direction of chemical reactions and determining whether a process is spontaneous. The formula for calculating Gibbs Free Energy is:



  • ΔG is the change in Gibbs Free Energy,
  • ΔH is the change in enthalpy,
  • T is the absolute temperature in Kelvin, and
  • ΔS is the change in entropy.

The calculator requires three inputs: the change in enthalpy (ΔH), the absolute temperature (T), and the change in entropy (ΔS). By inputting these values, the calculator can quickly compute ΔG, helping users understand the energetics of reactions or processes.

Step-by-Step Examples

Example 1: Suppose we want to calculate the Gibbs Free Energy for a reaction with the following parameters:

  • ΔH = -120 kJ (exothermic reaction),
  • T = 298 K (room temperature),
  • ΔS = 0.2 kJ/K.

Plugging these values into our calculator:

ΔG = (-120 kJ) – (298 K)(0.2 kJ/K) = -120 kJ – 59.6 kJ = -179.6 kJ.

The negative ΔG indicates that the reaction is spontaneous under the given conditions.

Example 2: For a reaction with ΔH = 50 kJ (endothermic), T = 350 K, and ΔS = -0.1 kJ/K:

ΔG = 50 kJ – (350 K)(-0.1 kJ/K) = 50 kJ + 35 kJ = 85 kJ.

A positive ΔG suggests the reaction is non-spontaneous at room temperature.

Relevant Information Table

Change in Gibbs Free EnergyΔGkJMeasures the spontaneity of a process; negative for spontaneous reactions.
Change in EnthalpyΔHkJHeat absorbed or released in a reaction; negative for exothermic reactions.
Absolute TemperatureTKTemperature in Kelvin; required for calculating ΔG.
Change in EntropyΔSkJ/KMeasure of disorder or randomness; positive when the disorder increases.


The Gibbs Free Energy Calculator is an essential tool for anyone studying or working in the field of chemistry or thermodynamics. It simplifies complex calculations, saves time, and aids in the quick assessment of reaction feasibility. Understanding the change in Gibbs Free Energy is crucial for predicting the behavior of chemical reactions and for designing processes that are thermodynamically favorable. This calculator not only enhances educational understanding but also supports research and industrial applications where quick and accurate energy calculations are necessary.

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