midterm+1+practice

midterm+1+practice - McKeachie Chem 1B Winter 08 - Practice...

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McKeachie Chem 1B Winter 08 - Practice problems for midterm 1 1. A compound contains only C, H, and N and has 58.51 % C and 7.37 % H by mass. Helium effuses 3.20 times faster than the compound does. Determine the empirical and molecular formula of the compound. 2. An aerosol spray can contains 400. mL of compressed gas at a pressure of 5.20 atm. When all the gas is sprayed into a large plastic bag, the bag inflates to a volume of 2.14 L. What is the pressure of gas inside the plastic bag? 3. A 2.00 L sample of O 2 (g) was collected over water in a laboratory at 25 °C with a specialized hood over the collection device, keeping the total pressure over the experiment at 785 Torr. When the O 2 is dried (water vapor removed), the gas inside the collection device contracts to a volume of 1.94 L at 25 °C and 785 Torr. Calculate the vapor pressure of water at 25 °C. 4. “Relief valves” are gas connection devices which prevent the pressure from reaching above a preset maximum. If the pressure of a system reaches this preset limit, the valve will be
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This note was uploaded on 02/09/2011 for the course CHEM 1B taught by Professor King during the Spring '08 term at UC Irvine.

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