2 greater than 34 torr 3 17 torr correct 4 between 17 and 34 torr 5 34 torr

# 2 greater than 34 torr 3 17 torr correct 4 between 17

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2. greater than 34 torr. 3. 17 torr. correct 4. between 17 and 34 torr. 5. 34 torr. Explanation: Partial pressures are a function of tempera- ture, not of volume. Since each container has the same temperature, the partial pressure of the gas in each will be the same as well. 015 10.0 points Consider the cesium chloride unit cell be- low. Cs Cl What is its empirical formula? 1. CsCl correct 2. Cs 2 Cl 3 3. Cs 3 Cl 2 4. CsCl 2 5. CsCl 3 6. CsCl 8 7. Cs 3 Cl 8. Cs 2 Cl Explanation: Eight chloride ions lie at the corners and one cesium ion lies in the center of the unit cell. Consider only the portion of the ions inside the unit cell: Cl : one within the cell = 1 Cl Cs : 8 corners × 1 8 atoms/corner = 1 Cs Cl Cl = 1 1 ; the empirical formula is CsCl, with one formula unit per unit cell. 016 10.0 points A certain liquid has a meniscus that curves downward in glass. This means that the cohe- sive forces in the liquid are less than the forces between the liquid and the glass. 1. False correct 2. True Explanation: 017 10.0 points How many atoms are there in a face-centered cubic unit cell? 1. 10 2. 6 3. 12 4. 8 5. 4 correct Explanation: 018 10.0 points The phase diagram for a pure substance is given below. kamalska (mk23835) – HW01 – Quigley – (104001) 6 Solid Liquid Vapor 50 100 150 200 250 300 100 200 300 400 Temperature, K Pressure, atm What is the lowest temperature at which liquid can exist? 1. 0 K 2. 150 K 3. 200 K correct 4. 400 K 5. 250 K Explanation: 019 10.0 points What are all of the intermolecular forces that are responsible for the existence of the molec- ular solid oxalic acid (H 2 C 2 O 4 )? 1. dipole-dipole and ion-ion 2. hydrogen bonding and dipole-dipole 3. London forces 4. dipole-dipole and London forces 5. dipole-dipole, London forces, and hydro- gen bonding correct Explanation: 020 10.0 points Estimate the enthalpy of vaporization of CCl 4 given that at 25 C and 58 C its vapor pressure is 107 and 405 torr, respectively. Assume that the enthalpy of vaporization is independent of the temperature. 1. 486 J · mol 1 2. 33.1 kJ · mol 1 correct 3. 142 kJ · mol 1 4. 3.98 kJ · mol 1 5. 48.6 kJ · mol 1 Explanation: T 1 = 25 C + 273 . 15 = 298 . 15 K P 1 = 107 torr T 2 = 58 C + 273 . 15 = 331 . 15 K P 2 = 405 torr Using the Clausius-Clapeyron equation, ln parenleftbigg P 2 P 1 parenrightbigg = Δ H vap R parenleftbigg 1 T 1 - 1 T 2 parenrightbigg Δ H 0 vap = R ln parenleftbigg P 2 P 1 parenrightbigg 1 T 1 + 1 T 2 = 8 . 314 J · mol 1 · K 1 298 . 15 K - 1 331 . 15 K × ln parenleftbigg 405 torr 107 torr parenrightbigg = 33109 . 5 J · mol 1 021 10.0 points A substance has a melting point of 1200 K. It conducts electricity while melting but not in the solid. This substance would be classified as 1. a hydrogen bonded solid. 2. a metallic solid. 3. a covalent network solid. 4. an ionic solid. correct 5. a molecular solid. kamalska (mk23835) – HW01 – Quigley – (104001) 7 Explanation: Ionic solids are held together by electro- static attractions between cations and anions.  #### You've reached the end of your free preview.

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• Fall '08
• QUIGLEY
• Van der Waals force, London Forces
• • • 