1. Lecture 3411/30/05

2. Vapor pressure vs. boiling point?

3. 1. What phase is xenon at room temperature? 2. If the pressure exerted on a sample of xenon is 0.75 atm and the temperature is -114 °C, in what phase does it exist? 3. If the vapor pressure of a sample of liquid xenon is 375 mm Hg, what is the temperature of the liquid phase? 4. What is the vapor pressure of solid xenon at -122 °C? 5. Which is the denser phase, solid or liquid?

4. 11-88 Liquid ammonia, NH 3 (l) was used as a refrigerant fluid before the discovery of chlorofluorocarbons and is still widely used today. Its normal boiling point is -33.4 °C, and its heat of vaporization is 23.5 kJ/mol. The gas and the liquid have specific heat capacities of 2.2 J/g-K and 4.7 J/g-K, respectively. How much heat must be supplied to 10.0 kg of liquid ammonia to raise its temperature from -50 °C to 0°C?

5. Given that the specific heat capacity of air is 1.0 × 10 3 J kg -1 K -1, calculate how much energy must be removed from a refrigerator containing 0.15 m 3 of air to lower the temperature of the air from 20 °C to 4 °C (assume density of air = 1.2 kg m -3 ).