## Half Life

$aR \to bP, Rate = -\frac{1}{a} \frac{d[R]}{dt} = \frac{1}{b}\frac{d[P]}{dt}$

Ethan Vuong 3G
Posts: 51
Joined: Fri Sep 29, 2017 7:07 am

### Half Life

Just generally, since each half life equation is different depending on which order it is in, are they essentially the same thing but based off of their respective rate laws?

Angela G 2K
Posts: 30
Joined: Fri Sep 29, 2017 7:06 am

### Re: Half Life

Half-life is just the time needed for the concentration to reach half its initial concentration. That definition is the same no matter the order of the reaction. To get the half-life equation from each different rate law, just set t=t1/2, and [A]=1/2 {A}0, and then just algebraically separate t1/2 from the equation.

Jasmin Tran 1J
Posts: 54
Joined: Thu Jul 27, 2017 3:00 am

### Re: Half Life

You can also see a Rate Law Summary in Table 15.2 in the book, and it shows a comparison of all three rate laws to see how they are related.

Diego Zavala 2I
Posts: 65
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

### Re: Half Life

Yes, the half-life represents the same concept in all the rate laws. The half-life equation varies according to the order of the reaction because the integrated rate laws depend on the order of the reaction