1.17 A sample of drinking water was...
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1.17 A sample of drinking water was found to be severely contaminated with chloroform, CHCI supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass). (i) Express this in per cent by mass. (ii) Determine the molality of chloroform in the water sample.

JEE/Engineering Exams
Chemistry
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(i) 1 ppm is equivalent to 1 part out of 1 million (106) parts. ( therefore ) Mass percent of 15 ppm chloroform in water ( frac{2}{6} times 10 ) ( =1.5 times 10^{-3} % ) (ii) molality ( (M)= ) no of moles of solute/mass of solvent in ( mathrm{g}^{star} 1000 ) Therefore mass of chloroform= ( 12+ ) ( 1+3(35.5)=119.5 mathrm{g} / mathrm{mol} ) ( 100 mathrm{g} ) of the sample contains ( 1.5 times ) ( 10^{-3} mathrm{g} ) of ( mathrm{CHCl}_{3} ) ( Rightarrow 1000 mathrm{g} ) of the sample contains ( 1.5 times ) ( 10^{-2} mathrm{g} ) of ( mathrm{CHCl}_{3} ) ( m=1.5 times 10^{-3} / 119.5 * 1000=1.25 x ) ( 10^{-4} mathrm{m} )
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