Final answer:
Rate laws are determined through experiments, specifically by measuring reaction rates at different reactant concentrations to establish the rate law and rate constant. The option (A) is correct.
Step-by-step explanation:
Rate laws are determined experimentally. The process involves performing a series of experiments with different starting concentrations of reactants and measuring the initial rate of the reaction. By comparing initial rates under varying reactant concentrations, scientists can deduce the order of the reaction concerning each reactant and the overall rate law equation, which includes the rate constant (k) and concentration terms raised to the power of their respective reaction orders.
The method of initial rates is a common experimental approach for determining rate laws. Once the rate law is established, it can be used to solve for the rate constant by substituting the data from any of the conducted experiments.
It is crucial to mention that rate laws cannot be predicted by the stoichiometry of the reaction but must be ascertained through experimental observation. The reaction mechanism is often deduced from the rate law and other experimental data. Therefore, option (A) is correct.