The molar mass of an insecticide dibromoethane is

This preview shows page 15 - 19 out of 110 pages.

39.The molar mass of an insecticide, dibromoethane, is 187.9 g/mol. Its molecular formula is C2H4Br2. What percent by mass of bromine does dibromoethane contain?A)42.52%B)2.14%C)85.05%
D)12.78%E)6.39%ANS: C PTS: 1 DIF: Easy REF: 3.6
KEY: Chemistry | general chemistry | stoichiometry | determining chemical formulas | mass percentage MSC: Quantitative40.Hydrocortisone valerate is an ingredient in hydrocortisone cream, prescribed for skin problems. Its molecular formula is C26H38O6. What is the percent by mass of carbon in hydrocortisone valerate?
KEY: Chemistry | general chemistry | stoichiometry | determining chemical formulas | mass percentage MSC: Quantitative41.Ammonium chromate, (NH4)2CrO4, contains what percent nitrogen by mass?
KEY: Chemistry | general chemistry | stoichiometry | determining chemical formulas | mass percentage MSC: Quantitative
42.You heat 3.854 g of a mixture of Fe3O4and FeO to form 4.148 g Fe2O3. The mass percent of FeO originally in the mixture was:
KEY: Chemistry | general chemistry | stoichiometry | determining chemical formulas | mass percentage MSC: Quantitative43.You take an aspirin tablet (a compound consisting solely of carbon, hydrogen, and oxygen)with a mass of 1.00 g, burn it in air, and collect 2.20 g of carbon dioxide and 0.400 g water. The molar mass of aspirin is between 170 and 190 g/mol. The molecular formula of aspirin isA)C6H8O5B)C9H8O4C)C8H10O5D)C10H6O4E)none of theseANS: B PTS: 1 DIF: Moderate REF: 3.7
KEY: Chemistry | general chemistry | stoichiometry | determining chemical formulas | elemental analysis | molecular formula MSC: Quantitative44.Suppose you are given the percent by mass of the elements in a compound and you wish to determine the empirical formula. Which of the following is true?
KEY: Chemistry | general chemistry | stoichiometry | determining chemical formulas | empirical formula MSC: Conceptual

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture