What is the effect of increasing concentration on the equilibrium of a chromate/dichromate mixture?

What is the effect of increasing concentration on the equilibrium of a chromate/dichromate mixture?

• A. It shifts the equilibrium to produce more chromate.
• B. It shifts the equilibrium to produce more dichromate.
• C. It has no effect on the equilibrium.
• D. It decreases the rate of the forward reaction.

Answer: (B)

In a chromate/dichromate equilibrium system, the reaction can be represented as follows: \[ \text{2 CrO}_4^{2-} (aq) \rightleftharpoons \text{Cr}_2\text{O}_7^{2-} (aq) + \text{H}_2\text{O} \] According to Le Chatelier's Principle, if the concentration of one of the reactants or products in a dynamic equilibrium is changed, the system will adjust itself to counteract that change. In this case, if the concentration of chromate ions (\( \text{CrO}_4^{2-} \)) is increased, the system responds by shifting the equilibrium to the right, toward the production of dichromate ions (\( \text{Cr}_2\text{O}_7^{2-} \)). This shift helps to decrease the concentration of chromate ions until a new equilibrium is reached. Thus, increasing the concentration of chromate ions effectively drives the reaction forward, resulting in the formation of more dichromate ions.

In a chromate/dichromate equilibrium system, the reaction can be represented as follows:

[ \text{2 CrO}_4^{2-} (aq) \rightleftharpoons \text{Cr}_2\text{O}_7^{2-} (aq) + \text{H}_2\text{O} ]

According to Le Chatelier's Principle, if the concentration of one of the reactants or products in a dynamic equilibrium is changed, the system will adjust itself to counteract that change. In this case, if the concentration of chromate ions (( \text{CrO}_4^{2-} )) is increased, the system responds by shifting the equilibrium to the right, toward the production of dichromate ions (( \text{Cr}_2\text{O}_7^{2-} )). This shift helps to decrease the concentration of chromate ions until a new equilibrium is reached.

Thus, increasing the concentration of chromate ions effectively drives the reaction forward, resulting in the formation of more dichromate ions.