Question 17 of 36intermediate🔧 ApplyNumerical5 marks

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) Express this in per cent by mass. (ii) Determine the molality of chloroform in the water sample.

(i)
Answer

1.5×10−3%1.5 \times 10^{-3} \%

(ii)
Answer

1.255×10−41.255 \times 10^{-4} m

Explanation

The question requires converting parts per million (ppm) to mass percentage and then calculating molality. 15 ppm means 15 g of solute in 10610^6 g of solution. For mass percentage, multiply the ratio by 100. For molality, calculate the moles of solute using its molar mass and divide by the mass of the solvent in kilograms.

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