Question #162555

Waste water from a cement factory contains 0.25 g of Ca2+ and 0.056 g of Mg2+ per 100.0 L of solution. The solution density is 1.001 g/mL. Calculate the Ca+2 and Mg +2 concentrations in ppt, ppm and ppb (by mass)

Expert's answer

The mass of 100L waste water solution is

(100L solution)×"\\frac{1ml}{10^{-3}L}" ×"\\frac{1.001g}{1ml}" = 1.001×10^{5} g

ppt = "\\frac{mass of solute}{mass of solution}" × 10^{12}

Ca^{2+ } ppt = "\\frac{0.25}{1.001\u00d710^5}" ×10^{12} = 2.5×10^{6} ppt

Mg^{2+} ppt = "\\frac{0.056}{1.001\u00d710^5}" × 10^{12} = 5.6×10^{5} ppt

ppm = "\\frac{mass of solute }{mass of solution}" ×10^{6}

Ca^{2+} ppm = "\\frac{0.25}{1.001\u00d710^5}" ×10^{6} = 2.5 ppm

Mg^{2+} ppm = "\\frac{0.056}{1.001\u00d710^5}" × 10^{6} = 0.56 ppm

ppb = "\\frac{mass of solute }{mass of solution}" ×10^{9}

Ca^{2+} ppb = "\\frac{0.25}{1.001\u00d710^5}" ×10^{9} = 2.5 × 10^{3} ppb

Mg^{2+} ppb = "\\frac{0.056 }{1.001\u00d710^5}" ×10^{9} = 5.6×10^{2} ppb

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