Question

A sample of drinking water was found to be severly contaminated with chloroform CHCI3 The level of contamination was 15ppm (by mass) (a)express this in percent by mass (b) determine the molarity of chloroform in the water sample. at mass c=12 , H=1 , CI=35.5​

Answer 1

Answer:

A sample of drinking water was found to be severely contaminated with chloroform, CHCl3, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass). ... (i) 1 ppm is equivalent to 1 part out of 1 million (106) parts.

Answer 2

15 ppm corresponds to 15 g chloroform in 1000,000 g of solution.

(i) Percent by mass =Mass of solutionMass of chloroform​×100

Percent by mass =1000,00015​×100=1.5×10−3%

(ii) Molality =Molar mass of chloroform ×(Mass of solution−mass of chloroform)Mass of chloroform​×1000 (all masses in g)

Molality =119.5×(1000,000−15)15​×1000=1.255×10−4 m.