Posted by Chris on Monday, January 21, 2013 at 9:53am.
This problem is 1st order for half life.
How long would it take for the concentration of cyclopropane to decrease to 50% of its initial value? to 25% of its initial value?
Rate constant is 9.2/s
I set up like this...
t1/2= 0.693/9.2/s= 0.075s at 50%
I can't figure out how to get the answer of 0.151s from 25%...

Chemistry  Steve, Monday, January 21, 2013 at 11:19am
if it reduces to 1/2 in .075s, it will reduce to 1/4 in twice that, or .151s.
The halflife is 0.075s, so since 1/4 = 2(1/2), it takes 2 halflives to fall to 25%.