🤓 Based on our data, we think this question is relevant for Professor Egolf's class at Penn State University Park.

The units of parts per million (ppm) and parts per billion (ppb) are commonly used by environmental chemists. In general, 1 ppm means 1 part of solute for every 106 parts of solution. Mathematically, by mass:

ppm = μg solute / g solution = mg solute / kg solution

In the case of very dilute aqueous solutions, a concentration of 1.0 ppm is equal to 1.0 μg of solute per 1.0 mL, which equals 1.0 g solution. Parts per billion is defined in a similar fashion. Calculate the molarity of each of the following aqueous

solutions.

d. 0.10 ppm DDT (C_{14}H_{9}Cl_{5}) in H_{2}O

We’re being asked to determine the molarity of DDT (C_{14}H_{9}Cl_{5}) in 0.10 ppm DDT in water. Let’s first define **ppm** and **ppb**.

• **1 ppm means 1 part of solute for every 10 ^{6} parts of the solution**

*in terms of solutions:*

$\overline{){\mathbf{p}}{\mathbf{p}}{\mathbf{m}}{\mathbf{=}}\frac{\mathbf{\mu}\mathbf{g}\mathbf{}\mathbf{s}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{t}\mathbf{e}}{\mathit{m}\mathit{L}\mathbf{}\mathbf{s}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{t}\mathbf{i}\mathbf{o}\mathbf{n}}}$

• **1 ppb means 1 part of solute for every 10 ^{9} parts of the solution**

ppm