Question

What is the rate constant of a first-order reaction that takes 5.50 minutes for the reactant concentration to drop to half of its initial value?

Answer 1

im assuming this is a decay function
5.5 is the half life
\[(1-r)^{5.5} = \frac{1}{2}\]
\[r = 1 - (\frac{1}{2})^{5.5}\]

Answer 2

oops just realized i had a typo
\[r = 1 - (\frac{1}{2})^{1/5.5}\]

Answer 3

well the answer is supposed to be .126

Answer 4

well in that case it must be an exponential decay
\[e^{-5.5k} = \frac{1}{2}\]
\[k = \frac{\ln (1/2)}{-5.5}\]