### 15.27

Posted:

**Sat Mar 03, 2018 4:43 pm**How do you calculate the time it takes for something to get to 15% of its initial concetration and 1/9th of its initial condition if you are given only its half life?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=145&t=28804

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Posted: **Sat Mar 03, 2018 4:43 pm**

How do you calculate the time it takes for something to get to 15% of its initial concetration and 1/9th of its initial condition if you are given only its half life?

Posted: **Sat Mar 03, 2018 5:27 pm**

You can assume that the initial concentration equals 1 and the final concentration you're looking for equals 0.15 when solving the half-life equation for time.

Posted: **Sat Mar 03, 2018 5:33 pm**

Using the given half-life, we can use the formula to calculate the k value. From there, we can use the formula to calculate time. [A]_{t} is the concentration remaining after time t.