A Chemical Equilibrium is a chemical reaction by which the rate of forward reaction equals the rate of reverse reaction. As soon as the reactants react to produce the products, the products start reacting to re-produce the reactants back. This process goes back and forth. As a result of this the chemical equilibrium reaction ends up the reactants and products are present at the same time. This process is called to be reversible and designated by double arrows separating the reactants from the products.

Example of a Chemical Equilibrium is given below:

N2 (g) + 3 H2 (g) ⇔2 NH3 (g) + Heat

N2 (g) + 3 H2 (g) are the reactants

2 NH3 (g) + Heat are the products

The graph below illustrates the progress of such chemical equilibrium:

https://www.toppr.com/bytes/everything-chemical-equilibrium/embed/#?secret=iNPXhlmlGx

The concentration of the reactants decreases per time, while the concentration of products increases per time till both of reactants and the products concentrations are leveling off and the rate of the forward reaction equals the rate of the reverse reaction and the concentrations of reactants and products will exhibit no further change.

https://sites.google.com/site/chem4hsc/the-acidic-environment/chemical-equilibrium

A Molecular Workbench illustrates the concept of the Chemical Equilibrium.

One has to follow the same procedure mentioned to access the Activity Center of the Molecular Workbench and select the Chemical Equilibrium simulation.

http://mw.concord.org/modeler/showcase/simulation.html?s=http://mw2.concord.org/public/student/chemicalreaction/equilibrium.html