Using the Ideal Gas Law and Previously Learned Concepts

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Using the Ideal Gas Law and Previously Learned
Concepts

• A gas that is 80.0 carbon and 20.0 hydrogen has
  a density of 1.339 g/L at STP. Use this info. to
  calculate its
• Molecular Weight in g/mol
• Empirical Formula
• Molecular Formula
• Answers
• MW 30.0 g/mol
• E.F. CH3
• M.F. C2H6

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Figure 5.11
Determining the molar mass of an unknown volatile
liquid
based on the method of J.B.A. Dumas (1800-1884)
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Dumas Method of Molar Mass
Problem A volatile liquid is placed in a flask
whose volume is 590.0 ml and allowed to boil
until all of the liquid is gone, and only vapor
fills the flask at a temperature of 100.0 oC and
736 mm Hg pressure. If the mass of the flask
before and after the experiment was 148.375g and
149.457 g, what is the molar mass of the
liquid? Answer Molar Mass 58.03 g/mol