# Question #31802

##### 1 Answer

Here's how you can do that.

#### Explanation:

Your first goal here will be to determine how many *grams* of amoxicillin you need in order to have in your target solution.

A solution's **parts per million** concentration, **ppm**, expresses the number of grams of solute present in

If you take water's density to be equal to

#5 color(red)(cancel(color(black)("mL"))) * "1 g"/(1color(red)(cancel(color(black)("mL")))) = "5 g"#

of water. Notice that because your solution contains a very, very small amount o amoxicillin, you can safely assume that the *mass of the solution* is equal to the *mass of the water*.

Now, a **for every**

#5 color(red)(cancel(color(black)("g water"))) * "20 g amoxicillin"/(10^6color(red)(cancel(color(black)("g water")))) = 1 * 10^(-4)"g amoxicillin"#

At this point, you should focus on determining the volume of amoxicillin solution that contains **for every**

You can thus say that you need

#1 * 10^(-4) color(red)(cancel(color(black)("g amoxicillin"))) * "100 mL stock"/(1color(red)(cancel(color(black)("g amoxicillin")))) = "0.01 mL stock"#

Therefore, you can prepare your solution by taking

This will get you