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Gibbs Free Energy: A Level Chemistry Definition

Alexandra Brennan

Written by: Alexandra Brennan

Reviewed by: Philippa Platt

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Last updated

Contents

  1. 1. What is Gibbs Free Energy?
  2. 2. Gibbs Free Energy Revision Resources to Ace Your Exams

What is Gibbs Free Energy?

Gibbs free energy (G) is a thermodynamic function that determines whether a reaction is spontaneous under constant temperature and pressure.

It is given by the equation:

ΔG = ΔH - TΔS

  • ΔG is the Gibbs free energy change

  • ΔH is the enthalpy change

  • T is the temperature in Kelvin

  • ΔS is the entropy change.

A reaction is thermodynamically feasible if ΔG < 0 (negative), meaning it can occur without external energy input. Even if ΔG is negative, the reaction may still be slow due to a high activation energy. Understanding Gibbs free energy is essential in A Level Chemistry for predicting reaction feasibility and exploring entropy, enthalpy, and equilibrium concepts.

Gibbs Free Energy Revision Resources to Ace Your Exams

For more information about Gibbs free energy check out the following resources:

Explore our A level Chemistry Revision Resources

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Author
Reviewer
Alexandra Brennan

Author: Alexandra Brennan

Expertise: Chemistry

Alex studied Biochemistry at Newcastle University before embarking upon a career in teaching. With nearly 10 years of teaching experience, Alex has had several roles including Chemistry/Science Teacher, Head of Science and Examiner for AQA and Edexcel. Alex’s passion for creating engaging content that enables students to succeed in exams drove her to pursue a career outside of the classroom at SME.

Philippa Platt

Author: Philippa Platt

Expertise: Chemistry

Philippa has worked as a GCSE and A level chemistry teacher and tutor for over thirteen years. She studied chemistry and sport science at Loughborough University graduating in 2007 having also completed her PGCE in science. Throughout her time as a teacher she was incharge of a boarding house for five years and coached many teams in a variety of sports. When not producing resources with the chemistry team, Philippa enjoys being active outside with her young family and is a very keen gardener

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