World of Chemistry

VII. Calculations based on Formulae

VII-V. Percent Composition Calculations

  1. (a)Determine the percent composition of ammonia gas, NH3.
    (b)Determine the percent composition of ammonium nitrate, NH4NO3.
    (c)Determine the percent composition of ammonium sulfate, (NH4)2SO4.
    (d)Determine the percent composition of urea, N2H4CO.

  2. Each of the compounds listed in question 8 contains nitrogen. They are used as fertilizers. For each of the compounds, which one has the highest percentage of nitrogen?
  3. Chlorine (Cl) is the active ingredient used to purify water in swimming pools. Three brands are available and each cost $0.50 per liter of water solutions of NaOCl.
    • Brand A contains 10 % OCl- by mass,
    • Brand B contains 7 % chlorine (Cl) by mass,
    • Brand C contains 14 % NaOCl by mass.

    Which of the three brands is the best buy?

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Rosamaría Fong, Instructor of Chemistry,
British Columbia Institute of Technology, Burnaby, B.C. Canada.

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Rosamaría Fong, Instructor of Chemistry
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