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Phase Equilibrium: Single Condensable Component Part 2

Phase Equilibrium: Single Condensable Component Part 2. Contributions by: John L. Falconer & Will Medlin Department of Chemical and Biological Engineering University of Colorado Boulder, CO 80309-0424 Supported by the National Science Foundation.

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Phase Equilibrium: Single Condensable Component Part 2

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  1. Phase Equilibrium:Single Condensable ComponentPart 2 Contributions by: John L. Falconer & Will MedlinDepartment of Chemical and Biological EngineeringUniversity of ColoradoBoulder, CO 80309-0424 Supported by the National Science Foundation

  2. A 5 L fixed volume container has 4.8 L liquid H2O and 0.2 L water vapor at 25°C. The container is sealed and heated to 250°C. It has, for safety reasons, a pressure-release diaphragm set at 4.5 MPa pressure. The saturation pressure of water at 250°C is 3.97 MPa. The diaphragm broke during heating and the contents were released. What happened? Gas pressure too high as water vaporized Gas pressure too high because saturation pressure increased with temperature Liquid expanded and created pressure as it filled the container, which could not expand

  3. A piston-cylinder contains air and water vapor at 10% relative humidity. Which is the correct plot of the partial pressure of water vs. temperature as the temperature increases at constant pressure? PH2O PH2O PH2O PH2O PH2O A B x start Temperature Temperature Temperature Temperature Temperature start x x x x start D C E start start

  4. A piston-cylinder contains air and water vapor at 10% relative humidity. Which is the correct plot of the partial pressure of water vs. temperature as the temperature decreases at constant pressure? PH2O PH2O PH2O PH2O PH2O A B x x x Temperature Temperature Temperature Temperature Temperature start start start start x start D C E x

  5. A piston-cylinder contains air and water vapor at 50% relative humidity. Which is the correct plot of the partial pressure of water vs. temperature as the temperature decreases at constant pressure? PH2O PH2O PH2O PH2O x start B A PH2O x x x x start Temperature Temperature Temperature Temperature start start start Temperature E D C

  6. A piston-cylinder contains air and water vapor at 50% relative humidity. Which is the correct plot of the partial pressure of water vs. temperature as the temperature decreases at constant pressure? PH2O PH2O PH2O PH2O PH2O A B x x x x start start start Temperature Temperature Temperature Temperature Temperature start D C E x start

  7. A piston-cylinder contains air and water vapor at 50% relative humidity. Which is the correct plot of the partial pressure of water vs. temperature as the temperature decreases at constant pressure? PH2O PH2O PH2O PH2O PH2O A B x x x Temperature Temperature Temperature Temperature Temperature start start start D C E x x start start

  8. A piston-cylinder contains air and water vapor at 50% relative humidity. Which is the correct plot of the partial pressure of water vs. temperature as the temperature decreases atconstant pressure? PH2O PH2O PH2O PH2O PH2O A B x x Temperature Temperature Temperature Temperature Temperature start start start D C E x x x start start

  9. Two piston-cylinders at the same pressure contain air and water vapor that is being cooled; one of these plots represents a system initially at 50% relative humidity and another plot initially at 90%. Which two plots represent these systems? A & B C & D A & C B & D PH2O PH2O PH2O PH2O A C B D x x x x Temperature Temperature Temperature Temperature start start start start

  10. A piston-cylinder contains air and water vapor at 20% relative humidity. Which is the correct plot of the pressure of water versus total pressure as total pressure increases at constant temperature? PH2O PH2O PH2O PH2O A B Pressure Pressure Pressure Pressure x C x D start x x start start start

  11. A piston-cylinder contains air and water vapor at 40% relative humidity. Which is the correct plot of water pressure vs. total pressure as the pressure increasesat constanttemperature? PH2O PH2O PH2O PH2O A B Pressure Pressure Pressure Pressure x start x C x D start x start start

  12. A piston-cylinder contains air and water vapor at 50% relative humidity. Which is the correct plot of the relative humidity of the system vs. temperature as the temperature decreases at constant pressure? RH RH RH RH RH Temp. Temp. Temp. Temp. Temp. x x x x x start D C B E A start start start start

  13. A small tank contains dry air at 25°C. A small beaker of water at 25°C is placed in the container, which is then sealed. The tank is well insulated. When equilibrium is reached, the air temperature is __________. slightly higher slightly lower the same 25°C

  14. A small tank contains air that is supersaturated with water vapor, but no liquid water is present. That is, the system is not at equilibrium. The tank is well insulated. A small perturbation causes it to go to equilibrium. The air temperature ____________. increases decreases remains the same Air & Water Vapor

  15. A drinking bird bobs its head because water evaporates from its head and cools it. Suppose a large glass container is placed over the drinking bird and the water beaker. The bird ____________. bobs faster bobs slower stops bobbing Nothing changes

  16. A drinking bird bobs its head because water evaporates from its head and cools it. Suppose a large class container is placed over the drinking bird and the water beaker. In a few minutes, the bird stops bobbing because ____________. bobs faster bobs slower stops bobbing Nothing changes

  17. In the fall the relative humidity is high in early morning, and as the temperature increases, the relative humidity decreases because ____________. saturation pressure of water increases water condenses water evaporates saturation pressure of water decreases

  18. A container has liquid water (10% of the volume) andwater vapor (90% of the volume) in equilibrium at2 atm. It is sealed so the volume is fixed. The temperature is raised. What happens? The liquid evaporates and the pressure increases The vapor condenses and the pressure increases The liquid and vapor remain to very high pressure Not possible to tell without additional information

  19. At room temperature you rapidly remove water vapor from an insulated container that contains 10% of the water as a liquid and the rest as a vapor. As the liquid level drops, the rate of vaporization with time ________. increases decreases stays constant since the surface area for evaporation is constant

  20. Liquid water is in equilibrium at 50°C with air in a piston-cylinder system. The total pressure is 1 bar. The pressure is raised to 2 bar by pushing down on the piston at constant temperature. At equilibrium, the partial pressure of the water ____________. increased   remained the same   decreased  

  21. Liquid water was super cooled to -15°C. In a well insulated system, it was then perturbed so it goes to equilibrium. What is the equilibrium state? All liquid at 0°C All solid at 0°C A mixture of liquid and solid at 0°C Liquid at a temperature higher than -15°C A mixture of liquid and solid at -15°C

  22. A container of fixed volume contains a mixture of liquid water and water vapor. You heat the container. What is the final condition (after adding enough heat)? All liquid All vapor Mixture of liquid and vapor Cannot be determined

  23. A container has liquid water (50% of the volume) and water vapor (50% of the volume) in equilibrium. It is sealed so the volume is fixed. The temperature is raised. What happens? The liquid evaporates and the pressure increases The vapor condenses and the pressure increases The liquid and vapor both remain (50:50) at a higher pressure All of the above are possible

  24. A 15 cm3 tank contains 5 cm3 of liquid water and 10 cm3of air and water vapor at 60°C. You add 5 cm3 more of liquid water and let it reach equilibrium at 60°C. The partial pressure of water ___________. increases decreases stays the same

  25. A 15 cm3 tank contains 5 cm3 of liquid water and 10 cm3of air and water vapor at 60°C. You add 5 cm3 more of liquid water and let it reach equilibrium at 60°C. The partial pressure of air___________. increases decreases stays the same

  26. One liter of liquid water is added to a 5-L closed, evacuated vessel (fixed volume) at 50°C. After equilibrium is reached, a second liter of liquid water was added. What happens? All the water is in the liquid state All the water is in the vapor state The water will still be in VLE

  27. For this single component P-V diagram, what is the fraction of the material that is liquid? 0.3 0.7 3/7 th System P x 0.3 0.7 V

  28. Weight Sealing lid Food inH2O A pressure cooker cooks food in a shorter time than an open pot by _______________. lowering the cooking temperature raising the boiling point of water using higher pressure to make food cook faster removing exposure of food to air raising the heat of vaporization for the water

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