Parts per million (ppm) is a way of expressing very dilute concentrations of substances

Practical Notes

• For dilute aqueous solutions, 1 ppm is roughly equal to 1 mg/L.
• For gaseous mixtures, 1 ppm is often taken as 1 µL of gas per liter of air.

Summary

PPM is a useful unit for measuring very small concentrations of a solute in a solution. The key point is to match the units correctly and multiply the ratio by 10 rast 6 to convert to ppm.