## 15.99

$\frac{d[R]}{dt}=-k; [R]=-kt + [R]_{0}; t_{\frac{1}{2}}=\frac{[R]_{0}}{2k}$

Blake_Katsev_2E
Posts: 113
Joined: Wed Sep 21, 2016 2:57 pm

### 15.99

Could somebody explain why graphing the half life vs. concentration of a zero order reaction is linear but not if its second order?

Natalie Rotstein 3J
Posts: 20
Joined: Wed Sep 21, 2016 2:59 pm

### Re: 15.99

For 0 order reactions, t1/2=[A]0/2k, which means t1/2 is proportional to A, which corresponds to a linear graph. For second order, however, t1/2=1/(k[A]0), which means t1/2 is proportional to 1/A - the graph of 1/x is not linear, so therefore the second order half life graph would also be nonlinear

Anna_Kim_2E
Posts: 31
Joined: Wed Sep 21, 2016 2:56 pm

### Re: 15.99

For second order, half life is t = 1/k[A]initial . Therefore, t (half life) and concentration have 1/[A] relationship.
Whereas, for zero order, half life t = [A]initial/2k , which shows that t(half life) and initial concentration direct linear relationship.