Equilibrium
MCAT glossary · Chemical & Physical Foundations of Biological Systems
Definition
The state in which forward and reverse reaction rates are equal and concentrations are constant.
Equilibrium in plain English
Equilibrium is when a reversible reaction reaches a steady balance — the forward reaction and the reverse reaction are still happening, but at the exact same speed, so the amounts of stuff stop changing. It's NOT that everything stopped; it's a busy standstill, like an escalator where people walk up at the same rate others ride down, so the crowd on each floor stays constant. Because the rates match, the concentrations of reactants and products lock in and hold steady even though molecules keep converting back and forth underneath.
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