Question

in the atmosphere, under the effect of ultraviolet rays, oxygen molecules combine to form ozone molecules, and ozone molecules also photodissociate to form oxygen molecules. which of the following would be observed if this reaction is in dynamic equilibrium?
the concentration of oxygen will increase.
the concentration of ozone will decrease.
the rates of the forward and reverse reactions will increase.
the rates of the forward and reverse reactions will remain the same.

Explanation:

To solve this, we recall the concept of dynamic equilibrium. In a dynamic equilibrium, the rate of the forward reaction (oxygen forming ozone) is equal to the rate of the reverse reaction (ozone photodissociating to oxygen). Also, the concentrations of reactants and products remain constant (not increasing or decreasing) at equilibrium.

• Option 1: In equilibrium, oxygen concentration doesn't increase as the reverse reaction (ozone to oxygen) balances the forward reaction (oxygen to ozone). So this is incorrect.
• Option 2: Ozone concentration doesn't decrease in equilibrium as the forward reaction (oxygen to ozone) balances the reverse reaction (ozone to oxygen). So this is incorrect.
• Option 3: The rates of forward and reverse reactions are equal, not increasing. So this is incorrect.
• Option 4: In dynamic equilibrium, the rate of forward reaction (oxygen → ozone) equals the rate of reverse reaction (ozone → oxygen), so their rates remain the same (equal) once equilibrium is reached. This matches the definition of dynamic equilibrium.

Answer:

The rates of the forward and reverse reactions will remain the same.