the concentration of a chemical degrades in water according to order kinetics. the degradation constant is 0.2 day^-1. if the initial concentration is 100.0 mg/L, how may days are required for the concentration to reach 0.14 mg/L?

You still didn't post the order. If we assume first order (a guess on my part) then

k = 0.693/t1/2
k = 0.693/0.2 = ??

ln(No/N) = kt
No = 100.0 mg/L
N =0.14 mg/L
k = from above.
t = unknown
Solve for t in days.

You didn't post the order.

The concentration of a chemical degrades in water according to order kinetics. the degradation constant is 0.2 day^-1. if the initial concentration is 100.0 mg/L, how many days are required for the concentration to reach 0.14 mg/L?

the answer should be 32.9 days...but im not getting tht

problem was it should be ln(N/No)=kt

thx tho DrBob222

dC/dt = - k Cln(C/Co) = - ktt = - ln(0.14/100) / 0.2 = 32.9 days

dC/dt = - k Cln(C/Co) = - kt

t = - ln(0.14/100) / 0.2 = 32.9 days
sorry this one written better