00:01
Particular reaction, we're told that the rate constant is 2 .4 times 10 to negative third, 1 over seconds, and that it's first order.
00:10
So we know that any first order reaction will have a constant half -life.
00:15
That's a really important fact about first -order reactions is that if you look at the equations for zero order and second order, those are often dependent on the concentration that you start with, whereas for a first order reaction, the half -life equation is actually just t1 -half equals 0 .693 over k, k being our rate constant.
00:42
And so basically just to find the half -life, we can plug in this number, and that gives us our half -life of 2 .4 times 10 to the negative third.
00:56
So t -1 -half equals 288 .75 seconds.
01:07
And so now it's asking how long will i take for 75 % to decompose? so we know that after one half -life, one half -life will have 50 % left...
