Question 6.4: A 1.00 g sample of stream water was found to contain 1.0 × 1...
A 1.00 g sample of stream water was found to contain 1.0 \times 10^{-6} g lead. Calculate the concentration of lead in the stream water in units of % (W/W), ppt, and ppm. Which is the most suitable unit?
weight percent: \% (\frac{W}{W} ) = \frac{grams of solute}{milliliters of solution} \times 100 \% \\ \qquad \qquad \qquad \quad \% (\frac{W}{W} ) = \frac{1.0 \times 10^{-6} g Pb}{1.0 g solution} \times 100 \% \\ \qquad \qquad \qquad \quad \% (\frac{W}{W} ) = 1.0 \times 10^{-4} \%
parts per thousand: ppt = \frac{grams of solute}{milliliters of solution} \times 10^3 ppt \\ \qquad \qquad \qquad \qquad ppt = \frac{1.0 \times 10^{-6} g Pb}{1.0 g solution} \times 10^3 ppt \\ \qquad \qquad \qquad \qquad ppt = 1.0 \times 10^{-3} ppt
parts per million: ppm = \frac{grams of solute}{milliliters of solution} \times 10^6 ppm \\ \qquad \qquad \qquad \quad ppm = \frac{1.0 \times 10^{-6} g \pmb{Pb}}{1.0 g solution} \times 10^3 ppm \\ \qquad \qquad \qquad \quad pm = 1.0 ppm
Parts per million is the most reasonable unit.