A sample of drinking water was found to be severely contaminated with chloroform (CHCl₃), supposed to be a carcinogen. The level of contamination was 15 ppm (by mass):
(i) express this in percent by mass
(ii) determine the molality of chloroform in the water sample.

Solution

Answer:

(i) 15 ppm of CHCl₃ in water means that there is 15 g of CHCl₃ in 10⁶ g of water (1 million = 10⁶)Percentage of CHCl_{3
$= \frac{15}{10^{6}} \times 100 = 0.0015 % = 1.5 \times 10^{- 4} %$}(ii)
Here we have already find the mass % is 15 x 10^-4

When even mass % is given take total mass of solution = 100 gram

And mass of solute (CHCl3) will = 15 x10^-4 g

Mass of solvent = mass of solution – mass of solute

(Here mass of solute is very small as compare to total mass of solution so neglect it and we get)

Mass of solvent = mass of solution

Mass of solvent = 100 g

Number of moles of solute = mass of solute / molar mass

number of moles of CHCl₃ = $\frac{15 \times 10^{- 4}}{118.5} = 1.266 \times 10^{- 5}$

Molality, m of CHCl3 in drinking water sample
$= \frac{moles of {CHCl}_{3}}{mass of water in kg}$

Now plug the value of number of moles and mass of solvent in above eqution

Here mass of solvent = 100 g

Convert it in Kg we divide by 100 we get

Mass of solvent = 0.1Kg

molaity = 1.266 x 10^-5/ 0.1 = 1.266 x 10^-4 mol Kg^-1

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?
(i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform, (vi) pentanol.

For Daily Free Study Material Join wiredfaculty

Solutions

A sample of drinking water was found to be severely contaminated with chloroform (CHCl₃), supposed to be a carcinogen. The level of contamination was 15 ppm (by mass):
(i) express this in percent by mass
(ii) determine the molality of chloroform in the water sample.

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?
(i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform, (vi) pentanol.

Two liquids A and B boils at 145⁰C and 190⁰C respectively. Which of them has a higher vapour pressure at 80⁰C ?

State the formula relating pressure of a gas with its mole fraction in a liquid solution in contact with it.

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Phone Number

Email Address

Loaction

For Daily Free Study Material Join wiredfaculty

Solutions

A sample of drinking water was found to be severely contaminated with chloroform (CHCl3), supposed to be a carcinogen. The level of contamination was 15 ppm (by mass): (i) express this in percent by mass (ii) determine the molality of chloroform in the water sample.

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 370C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?(i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform, (vi) pentanol.

Two liquids A and B boils at 1450C and 1900C respectively. Which of them has a higher vapour pressure at 800C ?

State the formula relating pressure of a gas with its mole fraction in a liquid solution in contact with it.

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

A sample of drinking water was found to be severely contaminated with chloroform (CHCl₃), supposed to be a carcinogen. The level of contamination was 15 ppm (by mass):
(i) express this in percent by mass
(ii) determine the molality of chloroform in the water sample.

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?
(i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform, (vi) pentanol.

Two liquids A and B boils at 145⁰C and 190⁰C respectively. Which of them has a higher vapour pressure at 80⁰C ?