Three elementary reactions were studied at the same temperature. Their experimentally determined rate laws are shown below, each accompanied by an unlabeled set of units for the rate constant.
Reaction I: rate=kI[A]2
Reaction II: rate=kII[B]1[C]2
Reaction III: rate=kIII[D]
Unlabeled unit sets:
Unit set P: mol−2L2s−1
Unit set Q: s−1
Unit set R: Lmol−1s−1
(a) Identify which unit set (P, Q, or R) corresponds to the rate constant for each reaction (I, II, III). State your reasoning in each case.
(b) For Reaction II, explain qualitatively why its rate constant must carry different concentration exponents in its units compared with Reaction III, even though both rate laws were measured at the same temperature.
(a) Match reactions to unit sets with justification.
(b) Conceptual explanation of differing rate-constant units.