Which statement best describes the rate constant?

Which statement best describes the rate constant?

• A. It is a measure of intrinsic reactivity and is experimentally determined
• B. It depends on temperature
• C. It is the same as the rate
• D. It is unrelated to the rate law

Answer: (A)

The rate constant is the proportionality factor that links the rate to the concentrations in the rate law; it encodes the inherent speed of the reaction at a given temperature. Because it reflects intrinsic reactivity, k is determined experimentally by measuring how fast the reaction proceeds for known concentrations and solving for k from the rate law. It is not the same as the rate itself, and it is a part of the rate law, not something unrelated to it. Note that k does depend on temperature (it changes if you heat or cool the system), but at a fixed temperature its value captures how readily the reaction occurs, independent of concentrations.

The rate constant is the proportionality factor that links the rate to the concentrations in the rate law; it encodes the inherent speed of the reaction at a given temperature. Because it reflects intrinsic reactivity, k is determined experimentally by measuring how fast the reaction proceeds for known concentrations and solving for k from the rate law. It is not the same as the rate itself, and it is a part of the rate law, not something unrelated to it. Note that k does depend on temperature (it changes if you heat or cool the system), but at a fixed temperature its value captures how readily the reaction occurs, independent of concentrations.