Unit 2 % Composition, Empirical, and Molecular Formulas Quiz -- Thurston High Chemistry

Multiple Choice (Choose the best answer.)

  1. A compound contains 6.0 g of cabon and 1.0 g of hydrogen. The percent composition of the compound is:

    14 % hydrogen and 86 % carbon

    86 % hydrogen and 14 % carbon

    17 % hydrogen and 83 % carbon

    83 % hydrogen and 17 % carbon

    None of these answers are correct.

  2. The empirical formula for the above reaction would be:

    CH2

    C2H

    C72H

    C2H5

    None of These

  3. Which of the following could be an empirical formula?

    N2O4

    N2H6

    N2O5

    More than one could be an empirical formula.

    None of these are empirical formulas.

  4. If the empirical formula of a compound is CH2 what is a possible molecular formula for the compound?

    CH2

    C2H6

    C4H8

    More than one could be a molecular formula for CH2.

    None of these could be a molecular formula for CH2.

  5. If the empirical formula of a compound is P2O3, what could be a possible molar mass of the compound?

    55 g/mol

    165. g/mol

    275. g/mol

    More than one could be a molar mass for P2O3.

    None of these could be a molar mass for P2O3.

  6. A compound is 40.0 % carbon, 53.3 % oxygen, and 6.66 % hydrogen. What is its empirical formula?

    C4O5H7

    C1O2H3

    C1O1H2

    More than one could be the correct empirical formula.

    None of these is the correct empirical formula.

  7. If the compound in problem 6 has a molecular weight equal to 60. g/mol, what is the molecular formula?

    C3O1H6

    C1O2H16

    C2O2H4

    More than one could be the correct molecular formula.

    None of these is the correct molecular formula.

  8. Which of the following sets of empirical formulas, molar masses, anad molecular formulas are correct?

    HO, 34 g/mol, H2O

    CH4N, 90 g/mol, C3H12N3

    CaO, 56 g/mol, Ca2O2

    C3H8O, 120 g/mol, C3H8O2

    CH, 78 g/mol, C13H13

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