The effective concentration of a species in a solution can be expressed precisely in terms of its activity. Activity considers the effect of electrolytes present in the vicinity of the species of interest and depends on the ionic strength of the solution. The activity of a species is expressed as the product of molar concentration and the activity coefficient of the species.
The thermodynamic equilibrium constant is more accurately defined in terms of activity rather than concentration. Activity is formally defined in terms of the chemical potential, also known as the partial molar Gibbs energy. The chemical potential of a system is the Gibbs energy change of the system per mole of a species in question, given that the temperature, pressure, and the number of moles of other species are held constant. For a chemical reaction to take place spontaneously, the chemical potential of the products must be less than that of the reactants. If the number of moles of other species varies in the solution—i.e., a change in the composition of the solution—the chemical potential of the solution changes, and so does the activity.
From Chapter 2:
Now Playing
Chemical Equilibria
785 Views
Chemical Equilibria
1.1K Views
Chemical Equilibria
1.2K Views
Chemical Equilibria
1.2K Views
Chemical Equilibria
485 Views
Chemical Equilibria
666 Views
Chemical Equilibria
583 Views
Chemical Equilibria
505 Views
Chemical Equilibria
412 Views
Chemical Equilibria
402 Views
Chemical Equilibria
291 Views
Chemical Equilibria
535 Views
Chemical Equilibria
895 Views
Chemical Equilibria
546 Views
Chemical Equilibria
392 Views
See More
Copyright © 2025 MyJoVE Corporation. All rights reserved
We use cookies to enhance your experience on our website.
By continuing to use our website or clicking “Continue”, you are agreeing to accept our cookies.