Advertisements
Advertisements
Question
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):
- express this in percent by mass.
- determine the molality of chloroform in the water sample.
Advertisements
Solution
(i) 15 ppm (by mass) means 15 parts per million (106) of the solution.
∴ Percent by mass = `15/10^6 xx 100`
= 1.5 × 10−3
(ii) Molar mass of chloroform (CHCl3) = 1 × 12 + 1 × 1 + 3 × 35.5
= 119.5 g mol−1
Now, according to the question,
15 g of chloroform is present in 106 g of the solution.
i.e., 15 g of chloroform is present in (106 − 15) ≈ 106 g of water.
Number of moles of CHCl3 = `"Mass (in g)"/"Molar mass"`
= `15/119.5`
∴ Molality of the solution = `(15/119.5 "mol")/(10^6) xx 1000`
= 1.25 × 10−4 m
APPEARS IN
RELATED QUESTIONS
Molarity of the solution is ____________.
The sum of all mole fraction for a mixture is always equal to ____________.
Molarity of liquid HCl will be if the density of the solution is 1.17 gm/cc.
An aqueous solution of glucose is 10% in strength. The volume in which 1 g mole of it is dissolved, will be:
10 g of NaCl is dissolved in 106 g of the solution. Its concentration is ____________.
2.5 litres of NaCl solution contain 5 moles of the solute. What is the molarity?
The mole fraction of the solute in one molal aqueous solution is ____________.
The volume of 4 N HCl and 10 N HCl required to make 1 litre of 6 N HCl are ____________.
For preparing 0.1 N solution of a compound from its impure sample of which the percentage purity is known, the weight of the substance required will be:
4 L of 0.02 M aqueous solution of NaCl was diluted by adding one litre of water. The molality of the resultant solution is ______.
What is the mole fraction of solute in 1.00 m aqueous solutions?
Define the following modes of expressing the concentration of a solution. Which of these modes are independent of temperature and why?
(iii) w/V (mass by volume percentage)
Carbon percentage (by weight) in crude petroleum may be about
What is the ratio of mass of an electron to the mass of a proton?
The de Broglie wavelength of a car of mass 1000 kg and velocity 36 km/hr is :
The unit of ebullioscopic constant is
3.36 M sulphuric acid solution is 29% H2SO4 calculate the density of the solution.
Calculate the mass percent of benzene (CoH6) and carbon tetrachloride (ccl4) if 22 g of benzene is dissolved in 122 g of carbon tetrachloride.
A 5% solution of \[\ce{Na2SO4.10H2O}\] (MW = 3 22) is isotonic with 2% solution of non- electrolytic, non volatile substance X. Find out the molecular weight of X.
