When acetic acid (CH₃CO₂H) and water (H₂O) interact, they produce hydronium cations (H₃O⁺) and acetate anions (CH₃CO₂⁻). The question asks about the rate of the reverse reaction immediately after adding more acetic acid to the system.
In general, the rate of a reaction depends on the concentrations of the reactants and the products. Just after adding acetic acid, there will be an increase in the concentration of acetic acid in the solution. This increase can shift the equilibrium of the reaction, which is described by Le Chatelier’s principle. It states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.
Specifically, since we have just increased the concentration of CH₃CO₂H, the reverse reaction (which converts H₃O⁺ and CH₃CO₂⁻ back to CH₃CO₂H and H₂O) will begin to occur more rapidly to rebalance the system. Therefore, the rate of the reverse reaction immediately after adding acetic acid will be:
- B) Greater than zero.
In summary, the addition of more acetic acid increases its concentration, which promotes the reverse reaction due to the system’s tendency to restore equilibrium.