Question

The rate law of a certain reaction is rate=k[X][Y]. The units of k, with measured in seconds, isA.) s^-1

B.) M^-1 s^-1
C.) M^-2 s^-1
D.) M^-1

Answer 1

The units of the rate constant 'k' for the given rate law rate = k[X][Y] are M^-2 s^-1, which ensures that the reaction rate is expressed in correct units of moles per liter per second (M/s).

Step-by-step explanation:

The rate law of a certain reaction is given by rate = k[X][Y] where 'rate' is the reaction rate, 'k' is the rate constant, and '[X]' and '[Y]' represent the molar concentrations of the reactants. To determine the units of the rate constant 'k', we must ensure that when we multiply 'k' by the concentrations of the reactants, we end up with units of reaction rate, which are moles per liter per second (M/s).

In this case, since the rate law involves the product of two concentration terms ([X] and [Y]), both with units of M (molarity), the units for 'k' would cancel out two molarity units to retain M/s as the final units. Therefore, the correct units for 'k' would be M-2 s-1, as this ensures that the overall reaction rate remains in units of M/s after multiplication with the concentration terms.