# What is the Difference Between Free Energy and Standard Free Energy

Understanding the difference between free energy and standard free energy is fundamental in the field of thermodynamics. Although both concepts are related to the energy of a system, they approach it from different perspectives.

What is the difference between free energy and standard free energy? Free energy represents the usable energy available in a system for doing work, whereas standard free energy represents the theoretical maximum usable energy under specific standard conditions.

### Key Areas Covered

1. What is Free Energy
– Definition, Features
2. What is Standard Free Energy
– Definition, Features
3. Similarities Between Free Energy and Standard Free Energy
– Outline of Common Features
4. Difference Between Free Energy and Standard Free Energy
– Comparison of Key Differences
5. FAQ: Free Energy and Standard Free Energy

### Key Terms

Free Energy, Standard Free Energy

## What is Free Energy

Free energy is the usable energy available to do work at a constant temperature.  It is denoted by the notation ΔG. Free energy considers two key factors – energy (how much there is) and disorder (entropy). A system naturally wants to increase its entropy, spreading out its energy. Free energy tells you how much usable energy is available while accounting for this tendency towards disorder.

If it is a spontaneous process (the process can happen on its own without external energy input) ΔG is said to be negative. This is because when the system releases unstable energy, it increases entropy.

If the process is non-spontaneous, ΔG is said to be positive. Charging a battery is an example – we put in electrical energy to overcome the positive ΔG and force the system into a lower-entropy state (stored chemical energy).

A negative ΔG suggests a reaction will proceed forward, while a positive ΔG indicates it won’t unless pushed by external energy.

## What is Standard Free Energy

Standard free energy is denoted by ΔG°. While regular free energy (ΔG) tells you the usable energy available under real-world conditions, ΔG° focuses on the maximum potential for a reaction assuming ideal conditions.

ΔG° assumes specific standard conditions:

• Temperature: 25°C (298 K) – a comfortable room temperature
• Pressure: 1 atm – typical atmospheric pressure
• Concentration: 1 M (1 mole per liter) for all reactants and products – a specific measure of how much stuff is dissolved.

These conditions are there to act as a consistent referent point in comparing reactions. It is said that when a reaction is thermodynamically favoirable, ΔG° is said to be negative.

The actual free energy (ΔG) might be lower or higher than standard free energy depending on factors like temperature, pressure, and concentration.

## Similarities Between Free Energy and Standard Free Energy

1. Both represent the energy available in a system to do work at a constant temperature.
2. Both quantities predict the thermodynamic favorability of a reaction.

## Difference Between Free Energy and Standard Free Energy

### Definition

• Free energy represents the actual usable energy available in a system under current conditions. On the other hand, standard free energy represents the theoretical maximum usable energy under a set of standardized conditions.

### Use

• Free energy predicts the direction of a reaction under the current conditions, while standard free energy predicts the thermodynamic favorability of a reaction under ideal conditions.

### Value

• Free energy is a dynamic value that changes as the reaction progresses and the system’s conditions change, whereas standard free energy is a constant value for a specific reaction at a specific temperature.

### Nature

• Free energy is applicable to real-world conditions, while standard free energy refers to theoretical conditions (25°C, 1 atm, 1 M concentrations).

## Conclusion

Free energy (ΔG) and standard free energy (ΔG°) both describe the usable energy available in a system for performing work, with ΔG applicable to real-world conditions and ΔG° referring to theoretical conditions (25°C, 1 atm, 1 M concentrations). This is the basic difference between free energy and standard free energy.

## FAQ: Free Energy and Standard Free Energy

### 1. What does ΔG∘f mean?

ΔGf is the change in free energy that occurs when 1 mol of a substance in its standard state is formed from the component elements in their standard states.

### 2. What are the two types of free energy?

Free energy comes in two types: the Helmholtz free energy F, sometimes called the work function, and the Gibbs free energy G. Gibbs Free Energy determines the spontaneity of a reaction at constant temperature and pressure, while Helmholtz Free Energy is relevant for systems with constant volume, measuring the maximum non-expansion work possible.

### 3. What are the 2 major types of energy?

The two major types of energy are kinetic energy and potential energy. Kinetic energy is the energy of motion, such as a windmill spinning in the wind. Potential energy is stored energy.

### 4. What are the sources of energy?

Energy comes from various sources, including fossil fuels like coal, oil, and natural gas, as well as renewable sources such as solar, wind, hydroelectric, and biomass. Nuclear energy, derived from the splitting of atoms in nuclear reactors, is another significant source, while geothermal energy harnesses heat from the Earth’s interior.

##### Reference:

1. “Free Energy.” Encyclopedia Britannica.
2. “Standard Gibbs Free Energy of Formation.” Wikipedia. Wikipedia Foundation.

##### Image Courtesy:

1. “Gibbs free energy changes” By Microbialmatt – Own work (CC BY-SA 4.0) via Commons Wikimedia

### About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.