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

15 ppm means 15 parts in million `(10^(6))` parts by mass in the solution
`therefore" % by mass "=(15)/(10^(6))xx100=15xx10^(-4)`
Taking 15 g chloroform in `10^(6)g` of the solution, mass of solvent `~=10^(6)g`
Molar mass of `CHCl_(3)=12+1+3xx35.5="119.5 g mol"^(-1)`
`therefore" Molality"=(15//119.5")/(10^(6))xx1000=1.25xx10^(-4)m.`
Promotional Banner

Topper's Solved these Questions

  • SOLUTIONS

    PRADEEP|Exercise NCERT (EXEMPLAR PROBLEMS WITH ANSWERS, HINTS AND SOLUTIONS) (MULTIPLE CHOICE QUESTIONS - I)|26 Videos

  • SOLUTIONS

    PRADEEP|Exercise NCERT (EXEMPLAR PROBLEMS WITH ANSWERS, HINTS AND SOLUTIONS) (MULTIPLE CHOICE QUESTIONS - II)|9 Videos

  • SOLUTIONS

    PRADEEP|Exercise NCERT (QUESTIONS AND EXERCISES WITH ANSWERS)|13 Videos

  • REDOX REACTIONS

    PRADEEP|Exercise Assertion reason type question|16 Videos

  • SOME BASIC CONCEPTS OF CHEMISTRY

    PRADEEP|Exercise Competition (FOCUS) JEE (Main and Advanced)/Medical Entrance SPECIAL (VIII. Assertion-Reason Type Questions)(Type II)|13 Videos

Similar Questions

Explore conceptually related problems

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.

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)

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.

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?

PRADEEP-SOLUTIONS-NCERT EXERCISES
  1. A solution is obtained by mixing 300 g of 25% and 400 g of 40% solutio...

    Text Solution

    |

  2. An antifreeze solution is prepared from 222.6 g of ethylene glycol [C(...

    Text Solution

    |

  3. A sample of drinking water was found to be severely contaminated with ...

    Text Solution

    |

  4. What role does the molecular interaction play in a solution of alcohol...

    Text Solution

    |

  5. Why do gases always tend to be less soluble in liquids as the temperat...

    Text Solution

    |

  6. State Henry's law and mention some of its imporant applications.

    Text Solution

    |

  7. The partial pressure of ethane over a saturated solution containing 6....

    Text Solution

    |

  8. What is meant by positive and negative deviations from Raoult's law an...

    Text Solution

    |

  9. An aqueous solution of 2 per cent (wt.//wt) non-volatile solute exerts...

    Text Solution

    |

  10. Heptane and octane form ideal solution. At 373 K, the vapour pressures...

    Text Solution

    |

  11. The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pr...

    Text Solution

    |

  12. Calculate the mass of a non-volatile solute ( molecular mass 40) which...

    Text Solution

    |

  13. A solution containing 30g of a non-volatile non-electrolyte solute exa...

    Text Solution

    |

  14. A 5% solution (by mass) of cane sugar in water has freezing point of 2...

    Text Solution

    |

  15. Two elements A and B form compounds having formula AB(2) and AB(4) . W...

    Text Solution

    |

  16. At 300 K, 36 g of glucose present per litre in its solution has an osm...

    Text Solution

    |

  17. Suggest the most important type of intermolecular interaction in the f...

    Text Solution

    |

  18. Suggest the most important type of intermolecular interaction in the f...

    Text Solution

    |

  19. Suggest the most important type of intermolecular interaction in the f...

    Text Solution

    |

  20. Suggest the most important type of intermolecular interaction in the f...

    Text Solution

    |