The instantaneous reaction rate of a hypothetical elementary irreversible chemical reaction abruptly — Chemical Kinetics Chemistry Question
Question
The instantaneous reaction rate of a hypothetical elementary irreversible chemical reaction $A \rightarrow \text{Products}$ abruptly scales up by an exact factor of $27$ whenever the concentration of pure reactant $A$ is precisely tripled. What is the fundamental kinetic order of this specific reaction?
💡 Solution & Explanation
Assume the rate law is $\text{Rate}_1 = k[A]^n$. When the concentration is tripled to $3[A]$, the new rate is $\text{Rate}_2 = k(3[A])^n = 3^n \times k[A]^n = 3^n \times \text{Rate}_1$. The problem specifies that $\text{Rate}_2 = 27 \times \text{Rate}_1$. Therefore, $3^n = 27$, which yields an integer order $n = 3$.