Posted by Odesa on .
N2O5 dissolved in CCl4 decomposes to give N2O4 and O2. The reaction is first order with a halflife of 1234 seconds. How long will it take, in seconds, for the concentration of N2O5 to fall to 1.1% of its initial value?

Chemistry 
DrBob222,
k = 0.693/t_{1/2}
ln(No/N) = kt
Use No = 100 (you can choose any number)
N = 100 x 0.011 = ?
k from above.
t = solve for this. 
Chemistry 
Anonymous,
DrBob222 explain better please

Chemistry 
Paul,
So what is it? or how to guide in filling in the date in the equation?

Chemistry 
Paul,
Thank you DrBob222,
the fraction left after t seconds is (1/2)^(t/1234)
(1/2)^(t/1234) = 0.011
t = 8028.84