Question #7ba62
1 Answer
Explanation:
Parts per million, or ppm, are used when dealing with very small concentrations of solute.
In simple terms, a concentration of one ppm is equivalent to one part solute per
#color(blue)("ppm" = "mass of solute"/"mass of solvent" xx 10^6)#
You can assume that one liter of rain water has a density of approximately
#"1 L" = "1 dm"^3 = 10^3"cm"^3#
you can say that one liter of rain water will have a mass of
#1color(red)(cancel(color(black)("L"))) * "1 g"/(1color(red)(cancel(color(black)("cm"^3)))) * (10^3color(red)(cancel(color(black)("cm"^3))))/(1color(red)(cancel(color(black)("dm"^3)))) = 10^3"g"#
So, you know that if you take the ratio between the mass of the solute and the mass of the solvent, and multiply the result by
#"ppm" = m_(CO_2)/m_"water" xx 10^6#
This means that the mass of the solute can be determined by rearranging the equation
#m_(CO_2) = ("ppm" xx m_"water")/10^6#
#m_(CO_2) = (355 * 10^3"g")/10^6 = 355 * 10^(-3)"g"#
If you want, you can express this value in miligrams
#m_(CO_2) = color(green)("355 mg")#