Which method can be used to determine the exponents in a rate law for a chemical reaction?

• A. By analyzing experimental data and determining how the rate changes with concentration
• B. By measuring the temperature dependence of the reaction
• C. By inspecting the balanced chemical equation
• D. By calculating the equilibrium constant

Answer: (A)

Verified step by step guidance

1. Understand that the exponents in a rate law represent the order of the reaction with respect to each reactant, and these cannot be determined simply by looking at the balanced chemical equation or equilibrium constant.
2. Recognize that the rate law is experimentally determined by measuring how the reaction rate changes when the concentration of one reactant is varied while keeping others constant.
3. Design experiments where you systematically change the concentration of each reactant and measure the initial rate of the reaction for each change.
4. Use the collected data to compare the rates and concentrations, applying the rate law formula \(\text{rate} = k [A]^m [B]^n\) where \(m\) and \(n\) are the exponents to be found.
5. Determine the exponents \(m\) and \(n\) by analyzing the ratio of rates and concentrations, often by taking logarithms or using the method of initial rates to solve for the reaction orders.