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# Gibbs Free Energy Calculator

Top
The Amount of energy, which has the capacity to to do work, which is acquired from a thermodynamic system is called Gibbs free energy. Gibbs free energy is calculated by using the formula ,
G = H + A - U
Where,
G = Gibbs free energy,
H = Enthalpy,
A = Helmoltz free energy,
U = Internal energy of the system.

## Steps

Step 1 : From the question, note down the values given.

Step 2 : Using the formula, substitute the given values and get the appropriate values accordingly.
G = H + A - U.

## Problems

Based on Gibbs free energy, some of the problems are solved below.

### Solved Examples

Question 1: Find the Gibbs free energy of the reaction given,
2H$_{2}$(g) + O$_{2}$(g) $\rightarrow$ 2H$_{2}$O(g).

If -241.8 KJ is the Enthalpy, 100 J is the Helmoltz free energy and 10 J is the Internal energy.
Solution:

Given : Enthalpy, H = -241.8 KJ,
Helmoltz free energy, A = 100 J,
Internal energy, U = 10 J

Gibbs free energy of the given reaction is,
G = H + A - U
G = - 241.8 KJ + 100 J - 10 J
G = - 151.8 KJ

Question 2: Find the Enthalpy of the reaction given,
C$_{2}$H$_{4}$(g) + H$_{2}$O(l) $\rightarrow$ C$_{2}$H$_{5}$OH(l).

If -6 KJ is the Gibbs free energy, -175 KJ is the Helmoltz free energy and 68 KJ is the Internal energy.

Solution:

Given : Gibbs free energy, G = -6 KJ
Helmoltz free energy, A = -175 KJ,
Internal energy, U = 68 KJ

Gibbs free energy of the given reaction is,
G = H + A - U
H = G - A + U
H = -6 KJ - (-175 KJ) + 68 KJ
H = 237 KJ