What is Dynamic Equilibrium?
Equilibrium is a constant state under a given set of conditions, but it can change to a different state if the conditions change. Notice here that equilibrium can change if the conditions change, so that’s why we call this dynamic equilibrium. Equilibrium systems are dynamic, in that they can respond to stresses or changes in conditions.
If the equilibrium system is stressed or the conditions change, a dynamic equilibrium can respond—or rather I should say equilibrium can respond and that’s why we call it a dynamic equilibrium. Now the French chemist Le Chatelier described how equilibrium responds to stress, so he came up with Le Chatelier’s principle which is: if a system at equilibrium is stressed, the equilibrium will shift in the direction that relieves this stress.
An equilibrium wants to be in a situation of little stress, so some common stresses include changes in (I’m going to write changes up here) changes in concentrations, and this could be in the concentrations of reactants or products; changes in pressure, now changes in pressure are only going to occur in reactions where gases are involved; and then also changes in temperature.
If any of these things change, then we consider this a stress and equilibrium here—equilibrium is stressed—so the equilibrium will shift in the direction that relieves this stress, so that it’s in a situation of little stress. One final note is that catalysts do not change the values of a system and equilibrium, it only changes how fast the system reaches equilibrium. Again, equilibrium is a constant state under a given set of conditions but can change to a different state if the conditions happen to change.