Swati Talwar


Chemical Equilibrium Study Guide

This is a crash course in chemistry for equilibrium that defines the equilibrium state in different conditions along with its characteristics.


The word equilibrium literally means "balance." Therefore, chemical equilibrium represents a state of balance in a chemical reaction. Chemical equilibrium is a state where there is no change in observable properties of the product involved in the process. Observable properties of a substance are its pressure, color, temperature, etc.

To put things in perspective, you can imagine melting ice at 0°C. In that state, both ice and water are present. However, melting of ice, dissolution of solute in solvent, etc., are examples of physical equilibrium. When a similar state is reached in a chemical reaction, it is termed a chemical equilibrium.


Chemical equilibrium Source

In a chemical reaction, equilibrium is achieved when the reaction is reversible. In cases as such, chemical equilibrium is defined as a state when the forward and backward reaction occurs at the same rate.

Alternatively, we may also define chemical equilibrium as a state where the volume of reactants and products does not change with time. In some cases, chemical equilibrium is also perceived as a stage where observable properties of the substances involved in the reaction do not change further with time when suitable conditions are provided.


Let's look at some of the properties of the equilibrium state:

  • When equilibrium is achieved in a chemical reaction, the number of reactants and products becomes equal. Therefore, one can start the reaction from either end.
  • When equilibrium is achieved at a given temperature, certain observable properties like pressure, density, color, etc., remain constant.
  • In order to achieve equilibrium, the chemical reaction must be reversible and must be conducted in a closed space.


  • Equilibrium means a state of balance.
  • In physical equilibrium, two states of matter can exist simultaneously. For example, melting of ice at 0 degrees Celsius.
  • Chemical equilibrium can be loosely defined as a state in a chemical reaction when there is no change in the observable properties.
  • Chemical equilibrium can be defined as a state in a reversible reaction where the rate of forward and backward reaction becomes equal.
  • We may also define chemical equilibrium as a state where there is no further change in the volume of reactants and products with time.
  • Lastly, chemical equilibrium is also said to be achieved when there is no observable change in the properties of the substances involved in the process.
  • To identify the equilibrium stage, take note of three characteristics:
  • An equal volume of reactants and products.
  • No change in observable properties with time.
  • The reversible reaction is carried out in closed space.


1. What is an equilibrium crash course?

A crash course on chemical equilibrium is a lesson plan that covers all the aspects of equilibrium briefly. The course mostly has an equilibrium video so that you can be exam ready within minutes.

2. How do you explain equilibrium in chemistry?

Chemical equilibrium is a state in a reversible chemical reaction when there is no change in the observable properties with time. For further details, you can join a chemistry crash course that will prepare you for your upcoming exams.

We hope you enjoyed studying this lesson and learned something cool about Chemical Equilibrium! Join our Discord community to get any questions you may have answered and to engage with other students just like you! Don't forget to download our App to experience our fun VR classrooms - we promise it makes studying much more fun! 😎


  1. Equilibrium: https://byjus.com/chemistry/equilibria/.Accessed 28 Feb 2022
  2. Equilibrium Crash Course: https://www.ck12.org/c/chemistry/chemical-equilibrium/lecture/Equilibrium:-Crash-Course-Chemistry/.Accessed 28 Feb 2022.