prelim_pract2

prelim_pract2 - What is the weight (in kg) of dry air used...

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Practice problems for Prelim 2, Fall 2007 1. You are working in a lab and you see a sealed 1 liter flask sitting on the lab bench. There is some liquid in the bottom of the flask. You recall that you boiled some liquid in that flask, driving off all air in the vapor space above the liquid. Then, you sealed the flask tight and let it cool to the lab temperature (30°C). However, you cannot recall whether it was ethanol or ethyl acetate that you boiled, and you forgot to label the flask (which is a serious violation of EPA rules!) Fortunately, the flask is fitted with a pressure gauge that reads 120 mm Hg. a) Write down a calculation that shows whether the material in the flask is ethanol or ethyl acetate. Explain your reasoning and state assumptions. b) You estimate there is 10 ml of liquid in the flask. What is the total mass in the flask?
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2. A drier must remove 200 kg H 2 O per hour from a certain material. Air at 22°C and 50% relative humidity enters the drier and leaves at 72°C and 80% relative humidity.
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Unformatted text preview: What is the weight (in kg) of dry air used per hour. The barometer reads 103 kPa. 3. A tank whose volume is 25.0 liter holds a mixture of 90 mole% CO and 10% CO 2 . The pressure gauge on the tank reads 2000 psi. Later, the pressure gauge reading has dropped to 1600 psi, indicating that the tank has a leak. The temperature in the room where the tank is located is 25°C. a) How many moles of gas have leaked out of the tank? (The gas in the tank is not ideal.) b) If the tank is in a closed room with a volume of 20.0 m 3 , estimate the maximum mole % of CO in the room, assuming the gas in the room is well mixed. 4. Methane (CH 4 ) is to be burned with 25% excess air. The methane is at 40 o C and 1.10 bar, and it is fed to the furnace at a rate of 500.0 m 3 /hr. The meter that reads the air flow rate is calibrated to read the volumetric flow rate of air at standard temperature and pressure. What will the meter read for this process?...
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This note was uploaded on 02/13/2008 for the course CHEM 3890 taught by Professor Hines, m during the Fall '08 term at Cornell.

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prelim_pract2 - What is the weight (in kg) of dry air used...

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