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molefraction_massfraction_extraproblems - (b μ g/L(c ppm...

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CEE 320 Additional problems on mass and mole fraction Environmental Engineering 17 February 2010 Use these problems to practice your understanding of mole and mass fractions. Answers are given in red . You should be able to work out a solution that allows you to arrive at that answer. Please ask for assistance if necessary, but we expect that you have attempted these problems on your own first. 1. A water sample contains 10 mg NO 3 - /L. What is the (a) concentration in moles/L, (b) mass fraction in ppm, and (c) mass fraction in ppb? (a) 1.6 × 10 -4 mol/L (b) 10 ppm (c) 10,000 ppb 2. Chlorophenols impart unpleasant taste and odor to drinking water at concentrations as low as 5 mg/m 3 . They are formed when the chlorine disinfection process is applied to phenol- containing waters. What is the threshold for unpleasant taste and odor in units of (a) mg/L,
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Unformatted text preview: (b) μ g/L, (c) ppm, and (d) ppb? (a) 5 × 10-3 mg/L (b) 5 μ g/L (c) 5 × 10-3 ppm (d) 5 ppb 3. Calculate the mole fraction of carbon monoxide (CO) with a concentration of 103 μ g/m 3 . State your answer in parts per billion. Assume a temperature of 25ºC and a pressure of 1 atm. 90 ppb 4. Ice-resurfacing machines use internal combustion engines that give off exhaust containing CO and NO x . Average CO concentrations measured in local ice rinks have been reported as high as 107 ppm and as low 36 ppm. How do these concentrations compare with an outdoor air quality standard of 35 mg/m 3 ? Assume a temperature of 20ºC. 107 ppm is equivalent to 125 mg/m 3 . 36 ppm is equivalent to 42 mg/m 3 . Both high and low average concentrations of CO in ice rinks are higher than the outdoor air quality standard of 35 mg/m 3 ....
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