ACS Chemistry Practice Exam 2026 – The All-in-One Guide to Exam Success!

Question: 1 / 400

If the concentration of a reactant in an equilibrium reaction is decreased, what is the expected effect on the equilibrium position?

Shift to the right

Shift to the left

When the concentration of a reactant in an equilibrium reaction is decreased, the system responds according to Le Chatelier's principle. This principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium will shift to counteract the change and restore balance.

In this case, reducing the concentration of a reactant causes the equilibrium to shift toward the side of the reaction that produces more of that reactant. This shift occurs because the system tries to increase the concentration of the reactant that has been reduced, hence the equilibrium position will move to the left, favoring the formation of reactants from products.

This principle emphasizes the dynamic nature of chemical equilibria and highlights how systems seek to maintain equilibrium despite changes in concentration, temperature, or pressure.

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No effect on the position

The reaction will stop

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