# A sample of drinking water was found to be severely contaminated with chloroform (CHCI3) supposed to be a carcinogen.

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A sample of drinking water was found to be severely contaminated with chloroform (CHCI3) supposed to be a carcinogen. The level of contamination was 15 ppm (by mass)

1. express this in percentage by mass

2. determine the molality of chloroform in the water sample.

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1. 15 ppm means 15 parts in million (106 ) parts by mass in the solution

% of mass = $\frac{15}{10^6}$ x 100 = 1.5 x 10-4

2. Taking 15g chloroform in 10g of the solution

Mass of the solvent = 106

Molar mass of CHCl3 = 12 + 1 + (3 x 35.5) = 119.5 g mol-1