For a first-order reaction, the initial reactant concentration is 0.722 M. After 48.5 min, the concentration is 0.501 M. What is k in min-1?

k is 9.1×10^-3 min^-1

Explanation:

Rate for a first-order reaction is kC

Rate = kC = change in concentration/time

C = 0.501 M

Co = 0.722 M

Change in concentration = Co - C = 0.722 - 0.501 = 0.221 M

Time = 48.5 min

k×0.501 = 0.221/48.5

0.501k = 4.56×10^-3

k = 4.56×10^-3/0.501 = 9.1×10^-3 min^-1