(a) For 1 m^3 of water and 1 m^3 of air each containing 1 g of benzene (C_6H_6),
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Question
(a) For 1 m^3 of water and 1 m^3 of air each containing 1 g of benzene (C_6H_6), give the benzene concentrations in the water in ppb and in the air in m at STP. (b) If you add 1 mL of a wastewater sample, which has an ultimate BOD of 960 ppm, to 300 mL of clean water with a DO concentration of 8.5 ppm in a sealed bottle, what would be the final DO concentration in the bottle after a sufficiently long incubation time? (c) The concentration of NO_2 in a combustion exhaust at 127 degree C and 1 atm is 23 mg/m^3. Give the concentration in ppm.Explanation / Answer
a) mass of benzene = 1 g = 1000 mg
mass of benzene = 1 g = 106 g
volume of water = 1 m3 = 1000 L
Molecular weight of Benzene = 78 g
Then,
parts per billion (ppb) = [mass of solute (g ) /volume of solution (L)]
= 106 g / 1000 L
= 1000 ppb
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At STP, parts per million (ppm) = [mass of solute (mg ) /volume of solution (m3)] x [24.5 / Molecular weight]
= [1000 mg/ 1 m3 ] x [24.5/ 78 g]
= 314 ppm
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