Gibbs free energy Calculator

[enthalpy] - [entropy] * [temperature]

Enthalpy

ΔH

Entropy

ΔS

Temperature

^{\degree C}

-1000

^{\degree C}

1000

^{\degree C}

([temperature]*9/5)+32

Fahrenheit

Gibbs free energy Formula

ΔG = ΔH - TΔS

Using Gibbs free energy Formula

				
					Where:
ΔG = Gibbs free energy
ΔH = Enthalpy change
T = Absolute temperature
ΔS = Entropy change

Notes On Gibbs free energy

Gibbs energy, also known as Gibbs free energy, is a thermodynamic potential that measures the maximum reversible work that can be performed by a system at constant temperature and pressure. It is denoted by the symbol G and is defined as the sum of the enthalpy (H) and the product of the temperature (T) and the entropy (S) of a system:

G = H - TS

Gibbs energy is a fundamental concept in thermodynamics and is used to determine whether a reaction will occur spontaneously at a given temperature and pressure. If the Gibbs energy of a system is negative, the reaction will occur spontaneously, releasing energy in the process. If the Gibbs energy is positive, the reaction will not occur spontaneously and will require external energy input to proceed.

The Gibbs Energy Research

Experimental research has been conducted to support the concept of Gibbs energy and its role in predicting the spontaneity of reactions. For example, a study by Ostwald in 1897 demonstrated the relationship between Gibbs energy and the equilibrium constant of a reaction. By measuring the equilibrium constant at different temperatures, Ostwald was able to calculate the Gibbs energy change of the reaction, showing that reactions with negative Gibbs energy are favored at equilibrium.

Another study by Gibbs himself in the late 19th century investigated the relationship between Gibbs energy and the maximum work that can be obtained from a system. Gibbs showed that the maximum work is equal to the free energy change of the system, providing a theoretical basis for the concept of Gibbs energy as a measure of the available energy in a system.

By calculating the Gibbs energy change of a reaction, scientists can predict the direction and feasibility of a reaction, making it an essential tool in chemical thermodynamics.

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Worked Example on Gibbs free energy

Let's assume we have a reaction with an enthalpy change of -200 kJ/mol and an entropy change of 50 J/(mol·K). If the temperature is 298 K, calculate the Gibbs free energy change for the reaction.

Given
ΔH = -200 kJ/mol
ΔS = 50 J/(mol·K)
T = 298 K

Plug in the values into the formula:

ΔG = -200 kJ/mol - (298 K)(50 J/(mol·K))
ΔG = -200 kJ/mol - 14900 J/mol
ΔG = -200 kJ/mol - 14.9 kJ/mol
ΔG ≈ -214.9 kJ/mol

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Practice Questions on Gibbs free energy

1. Calculate the change in Gibbs free energy when a reaction releases 100 kJ of heat at a temperature of 25°C.

2. At what temperature will a reaction become spontaneous if the change in Gibbs free energy is -200 kJ?

3. A reaction has a change in Gibbs free energy of 50 kJ and a change in entropy of -100 J/K. Calculate the temperature at which the reaction will be at equilibrium.