☰
Some Basic Concepts of Chemistry
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 is percent by mass.
(ii) Determine the molality of chloroform in the water sample.
i) 1ppm is equivalent to 1 part out of 1 million (106) parts.
Therefore, mass percent of 15 ppm chloroform in water
= (15/106) x100 =1.5 x 10-3 %
ii) 100 g of the sample contains 1.5 x 10-3 g of CHCl3.
1000 g of the sample contains 1.5 x 10-2 g of CHCl3
Thus, Molality of chloroform in water
= 1.5 x 10-2 g/Molar mass of CHCl3
Molar mass of CHCl3 =12+1+3(35.5)
=119.5 g mol-1
Therefore, molality of chloroform in water =0.0125 x 10-2 m
=1.25 x 10-4 m
Sponsor Area
Express 0.0468 in scientific notation.
What does SI units stand for?
What is the relation between temperature in Kelvin (K) and temperature on centigrade scale?
The popular unit of pressure is atmosphere, how is it related to pascal?
What are SI units of the following:
(i) Density
(ii) Molarity
(iii) Energy
(iv) Temperature ?
Out of 5.00 g and 5.0 g which one is more accurate and why?
What is iodised table salt?
Under what conditions air is considered as a heterogenous mixture?
What is gun powder?
Sponsor Area
Sponsor Area