## half life

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

Peter Nguyen 2I
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

### half life

In what situation would we use the half life equation?

705170809
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am
Been upvoted: 1 time

### Re: half life

It really depends on what information the problem provides you with, but one example would be if it asked you to calculate how long it takes for the reactant concentration to decrease by half. Another one would be like if they gave you the order and the actual half life, and you have to calculate for K to use in another part of the problem.

Valeria Viera 1B
Posts: 60
Joined: Fri Apr 06, 2018 11:05 am

### Re: half life

You should use half life if there’s a questions asking how long does it take for the concentration of “A” to get to a certain percentage of its original concentration
Or when a questions asks how much of A concentration is left after certain years if it’s half life is 10 years or so, for example.