Question

When does the equivalence point occur for an introductory activity?

a) When the reactants are completely used up
b) When the reaction rate slows down
c) When the reaction starts
d) When the products are formed

Answer 1

The equivalence point occurs when the reactants are completely used up, and the stoichiometric amounts of reactants and products are present, not to be confused with the equilibrium point where reactant and product concentrations remain constant over time.

Step-by-step explanation:

The equivalence point in an activity or chemical reaction occurs when the reactants are completely used up, and the stoichiometric amount of reactants and products are present. This is not to be confused with the equilibrium point, which occurs when the reaction reaches a state where the concentrations of reactants and products remain constant over time.

During the progression towards equilibrium, initially, the reactants are consumed to form products, and the rate of the forward reaction decreases as the reactant concentrations decrease. Concurrently, as products form, the reverse reaction rate increases. When the rates of the forward and reverse reactions become equal, chemical equilibrium is reached. At this dynamic equilibrium, the concentrations of reactants and products do not change, indicating that the reaction is ongoing but at a net change of zero. However, at the equivalence point, it is a one-time condition where equivalent quantities of reactants have reacted.