WS3 - Chem 142 Name Worksheet 3 Stoichiometry Summer 2011...

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Unformatted text preview: Chem 142 Name ________________________________________ Worksheet 3: Stoichiometry Summer 2011 Section ________________ 1. Calculate the average atomic mass of Zirconium (Zr). 90Zr (51.45%), 91Zr (11.27%), 92Zr (17.17%), 94Zr (17.33%),96Zr (2.78%). 2. Sucrose is the common sugar used in all homes, and chemical analysis tells us that the chemical composition is 42.14% carbon, 6.48% hydrogen and 51.46% oxygen. What is the molecular formula of sucrose if its molar mass is approximately 340 g/mol? 3. Determine the empirical and molecular formulas for a deadly nerve gas that gives the following mass percent analysis. C = 39.10% H = 7.67% O = 26.11% P = 16.82% F = 10.30% The molar mass is known to be 184.1 g/mol. 4. Erythrose (M = 120 g/mol) is an important chemical compound used often as a starting material in chemical synthesis and contains carbon, hydrogen, and oxygen. Combustion analysis of a 700.0 mg sample yielded: 1.027 g CO2 and 0.4194 g H2O. Determine the molecular formula. 5. A combustion device was used to determine the empirical formula of a compound containing ONLY carbon, hydrogen and oxygen. A 0.6349 g sample of the unknown produced 1.603 g of CO2 and 0.2810 g H2O. Determine the empirical formula of the compound. Assuming the empirical and molecular formulas are the same, what is the balanced chemical reaction for the combustion of this liquid? Page 1 of 1 ...
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