Dynamic Equilibrium

A reversible reaction that takes place in a closed container will eventually reach a state called dynamic equilibrium. This is when the forward and reverse reactions occur at the same rate, so the concentrations of the reactants and products remain constant.

A beaker labeled 'evaporation' has red circles rising from its opening, symbolizing vapor. Another beaker labeled 'equilibrium' contains red liquid and red circles, covered by a grey sheet. Two arrows, one pointing up and the other down, indicate the contained materials.

Dynamic equilibrium can only be reached in a closed system. In an open system, gases formed as products can escape and disrupt the equilibrium.

To understand how the forward and reverse reactions reach equilibrium, look at the diagram below.

A graph with the y-axis labelled "rate" and the x-axis labelled "time". A ascending line labelled "reverse rate" and a descending line labelled "forward rate" meet in the middle of the graph.

Initially, only the reactants are present, so the forward reaction is at its highest rate. As the reaction progresses, the concentration of the reactants decreases, causing the rate of the forward reaction to also decrease. On the other hand, the concentration of the products increases, leading to an increase in the rate of the reverse reaction.

Eventually, the rates of the forward and reverse reactions become equal, and at this point, equilibrium is reached.