# Question #41fbf

##### 1 Answer

That depends on what the volume of the initial solution is.

#### Explanation:

In order to be able to determine how much water is needed to reduce your solution's osmolarity from **520 mOsmol/L** to **300 mOsmol/L**, you need the actual volume of the initial solution.

Osmolarity expresses the number of *osmoles* per liters of solution.

In your case, you need to go from a *more concentrated* solution to a *diluted* solution. Let's assume that you have

The number of osmoles this solution would contain would be equal to

Now, let's assume that

This is equivalent to

where

So, to get how much water you need to add, simply multiply the initial volume by **0.73**.

For example, if you start with a **1-L** solution, you need to add

of water to go from 520 mOsmol/L to 300 mOsmol/L.

This of course implies that the volume of the *final solution* will be