Question

What are the units of k in the following rate law?

Answer 1

B.
`(1)/(M^(2) s )`

Step-by-step explanation:

The unit for rate is M/s while the unit for each molecule should be M. You can find the unit for k by putting the units for rate and the molecules into the equation

rate= k{X][Y]

M/s= k *
`M^(2)` *
`M^(1)`

k= (M/s) / (
`M^(3)`)

k=
`(1)/(M^(2) s )`

You can also use this predetermined formula to solve this problem faster: k=
`(M^(1-n) )/(s )`

Where n is the number of molecule. There are 3 molecule(2X and 1Y) so n=3, so

k=
`(M^(1-n) )/(s )`

k=
`(M^(1-3) )/(s )`=
`(m^(-2))/(s)`=
`(1)/(M^(2) s )`