What describes how the rate of reaction depends on the concentration?

• A. Integrated rate law
• B. Energy diagram
• C. Differential rate law
• D. Catalyst

Answer: (C)

The rate of a reaction as it changes with concentration is described by the differential rate law. This expresses the instantaneous rate in terms of the concentrations of the reactants, typically in a form like -d[A]/dt = k [A]^m [B]^n, where the exponents show how sensitive the rate is to each concentration (the reaction order with respect to each reactant). The integrated rate law, by contrast, links concentration to time and is derived from the differential rate law. An energy diagram illustrates energy changes and activation barriers, not how rate depends on concentration. A catalyst speeds up the reaction by lowering activation energy, but it doesn’t by itself define how the rate depends on concentration.