In a chemical reaction, chemical equilibrium is the state in which both reactants and products are present at concentrations which have no further tendency to change with time. Usually, this state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but equal. Thus, there are no net changes in the concentrations of the reactant(s) and product(s). Such a state is known as dynamic equilibrium.
Heat is energy flowing from a high temperature object to a low temperature object. When the two objects are at the same temperature, there is no net flow of energy or heat. That is why a covered cup of coffee will not be colder than or warmer than the room temperature after it has been in there for a few hours. This phenomenon is known as equilibrium. In this example, we deal with the flow of energy.
Equilibria happen in phase transitions. For example, if the temperature in a system containing a mixture of ice and water is uniformly 273.15 K, the net amount of ice formed and the melt will be zero. The amount of liquid water will also remain constant, if no vapour escape from the system. In this case, three phases, ice (solid) water (liquid), and vapour (gas) are in equilibrium with one another. Similarly, equilibrium can also be established between the vapour phase and the liquid at a particular temperature. Equilibrium conditions also exist between solid phase and vapour phases. These are phase equilibria.
Mr. Lalit Sardana(IIT-JEE AIR 243) will help you to understand Chemical equilibrium through this video. He will explain the equilibrium graph and properties of chemical equlibrium in detail and if you find something difficult then you may drop your comments or questions in the comment box or Ask module respectively. This topic is asked in 11th CBSE, 12th CBSE, JEE Mains, JEE Advanced, VITEEE, AIPMT, AFMC, MPPET, CET, KCET,etc.
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