To determine the reaction order with respect to a specific reactant, what procedure should you follow?

• A. Vary the concentration of that reactant while keeping others constant and observe how the rate changes; the exponent is the order with respect to that reactant.
• B. Vary all concentrations simultaneously and fit the data to a rate equation.
• C. Keep that reactant concentration fixed and vary the others, then observe the rate.
• D. Use equilibrium constants to infer the order from stoichiometry.

Answer: (A)