Dynamic nature of equilibrium

It helps to picture chemical equilibrium through an everyday analogy. Imagine people moving back and forth between the first and second floor of a multi-storey building -- some number of people move up from the first floor to the second in a given interval of time, and (say) the very same number of people move back down from the second floor to the first in that same interval. Because these two flows exactly balance, the number of people on each floor stays constant over time even though people never stop moving between the floors -- the population of each floor is in a dynamic equilibrium. …