Home
Class 12
CHEMISTRY
A sample of drinking water was found to ...

A sample of drinking water was found to be severely contaminated with chloroform, `CHCl_(3)`, supposed to be carcinogen. 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.

Text Solution

Verified by Experts

(i) 15 ppm means 15 parts in million `(10^(6))` parts
`therefore" "%" by mass "=(15)/(10^(6))xx100=15xx10^(-4)=1.5xx10^(-3)%`
(ii) Molar mass of chloroform `(CHCl_(3))=12+1+3xx35.5=118.5g mol^(-1)`
`"100 g of the sample contain chloroform"=1.5xx10^(-3)g`
`therefore" 1000 g (1 kg) of the sample will contain chloroform "=1.5xx10^(-2)g=(1.5xx10^(-2))/(118.65)" mole"`
`=1.266xx10^(-4)" mole"`
`therefore" Molality "=1.266xx10^(-4)m`.
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • SOME BASIC CONCEPTS OF CHEMISTRY

    PRADEEP|Exercise NCERT (EXEMPLAR PROBLEMS WITH ANSWERS, HINTS AND SOLUTIONS) (NCERT EXEMPLAR PROBLEMS CHAPTER 1) SOME BASIC CONCEPTS OF CHEMISTRY (MULTIPLE CHOICE QUESTIONS - I)|15 Videos

  • SOME BASIC CONCEPTS OF CHEMISTRY

    PRADEEP|Exercise NCERT (EXEMPLAR PROBLEMS WITH ANSWERS, HINTS AND SOLUTIONS) (NCERT EXEMPLAR PROBLEMS CHAPTER 1) SOME BASIC CONCEPTS OF CHEMISTRY (MULTIPLE CHOICE QUESTIONS - II)|7 Videos

  • SOME BASIC CONCEPTS OF CHEMISTRY

    PRADEEP|Exercise CONCEPTUAL QUESTIONS|16 Videos

  • SOLUTIONS

    PRADEEP|Exercise IMPORTANT QUESTIONS FOR BOARD EXAMINATION|31 Videos

  • SURFACE CHEMISTRY

    PRADEEP|Exercise IMPORTANT QUESTIONS (FOR BOARD EXAMINATION)|28 Videos

Similar Questions

Explore conceptually related problems

A sample of drinking water was found to be serverly contaminated with chloroform, CHCl_(3) , supposed to be 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.

A sample of drinking water was found to be severely contaminated with chloroform, CHCl_(3) , which is supposed to be carcinogenic in nature. The level of contamination was 15 pp m (by mass). a. Express this is precent by mass. b. determine the molarity of chloroform in the water sample.

Knowledge Check

  • A sample of drinking water severely contaminated with chloroform, CHCI_3 is supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass). What is the molality of chloroform in the water sample?

    A
    `2.25 xx 10^(-5)m`
    B
    `1.25 xx 10^(-4) m`
    C
    `1.85 xx 10^(-6) m`
    D
    `1.72 xx 10^(-5) m`

  • The domestic water supply is treated by bleaching powder to remove unhygienic species in water and to make it safe for drinking water. However, this given rise to Ca^(2+) and Cl^(-) ion contamination in water. Both these ions are also injurious for health if a minimum concentration is crossed. The chloride ions are tested by a kit provided by many companies having AgNO_(3) solution that is added drop by drop to 23 mL of water sample to which an indicator has been added. When sufficient silver nitrate is added to remove Cl^(-1) ions as AgCl solid, the solid turns orange. The colour change is noticed by addition of AgNO_(3) having molar concentration such that each drop (0.05 mL) of AgNO_(3) converts 12.5 mg of Cl^(-) ions AgCl . If 12 drops of AgNO_(3) solution are used to reach the colour point, what mass of chloride ion is present in one litre sample?

    A
    `6.52 g`
    B
    `7.150 g`
    C
    `5.125 g`
    D
    `1.25g`

    • Similar Questions

    Explore conceptually related problems

    What will be the molarity of chloroform in the water sample which contains 15 ppm chloroform by mass?

    1.0g of a sample containing NaCl, KCl and some inert impurity is dissolved in excess of water and treated with excess of AgNO_(3) solution. A 2.0 g precipitate to AgCl separate out. Also sample is 23% by mass in sodium. Determine mass percentage of KCl in the sample :

    Water contaminated with H_(2)S can be freed from H_(2)S by passing Cl_(2) through it. If the H_(2)S content in contaminated water is 22 ppm by mass how much Cl_(2) is needed to remove all the H_(2)S from 2xx10^(2) gallons of water. (1 gallon =3.785 litre)

    2.0 g of a sample containing NaCl, NaBr and some inert impurity is dissolved in enough water and treated with excess of AgNO_(3) solution. A 3.0g of precipitate was formed. Precipitate on shaking with aqueous NaBr gains 0.76 g of weight. Determine mass percentage of NaCl in the original sample.

    A student collected three samples of water from different sources and found out the percentage of hydrogen and oxygen by mass in thse samples. It should have been 1 : 8 by mass. But it was different in all three samples, Moreover, the values did not match (i) In your opinion why did the student get different results for different samples ? (ii) What should have been done by him ? (iii) Which law of chemical combination is supported by these observations (iv) How will you check the purity of water in the laboratory ?

    One litre of a sample of hard water contains 1 mg of CaCl_(2) and 1 mg of MgCl_(2) . Find the total hardness of water in terms of parts of CaCO_(3) per 10^(6) parts of water by mass.

    Home
    Profile