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# Exam3 - Version 297 Exam 3 Sutclie(53120 This print-out...

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Version 297 – Exam 3 – Sutcliffe – (53120) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. This exam IS ONLY to be taken by students in the 2-3pm MWF class. DO NOT START THIS EXAM if you do NOT attend the 2- 3pm MWF class. AVOGADRO’S NUMBER = 6.022 x 10 23 001 10.0 points For the reaction 2 HCl + Na 2 CO 3 2 NaCl + H 2 O + CO 2 what volume of 0 . 45 M HCl solution would be needed to produce 2 . 5 L of CO 2 at STP? 1. 2.5 × 10 2 mL 2. 1.2 × 10 2 mL 3. 4.5 × 10 2 mL 4. 7.5 × 10 2 mL 5. 2.2 × 10 2 mL 6. 5.0 × 10 2 mL correct Explanation: m HCl = 0 . 45 mol V = 2 . 5 L of CO 2 ? mL HCl = 2 . 5 L CO 2 × 1 mol CO 2 22 . 4 L CO 2 × 2 mol HCl 1 mol CO 2 × 1 L 0 . 45 mol HCl × 1000 mL 1 L = 496 . 032 mL . 002 10.0 points A drop of liquid tends to have a spherical shape due to the property of 1. capillary action. 2. close packing. 3. vapor pressure. 4. viscosity. 5. surface tension. correct Explanation: Molecules on the surface of a liquid are influenced by intermolecular attractions to- wards the interior; these attractions pull the surface layer toward the center. The most sta- ble situation is one in which the surface area is minimal. For a given volume, a sphere has the least possible surface area. 003 10.0 points A metal bulb is filled with 10.2 g of CHCl 3 and 1.67 g of CH 4 (two gases). What is the total pressure in the bulb if the temperature is 345 C and the volume is 50.0 mL? 1. 12.1 atm 2. 193 atm correct 3. 0.107 atm 4. There is no pressure because the metal bulb exerts more force than the gas does. 5. 12,030 atm 6. 107 atm 7. 1450 atm Explanation: n CHCl 3 = 10 . 2 g · mol 119 . 5 g = 0 . 0854 mol n CH 4 = 1 . 67 g · mol 16 g = 0 . 104 mol n total = 0 . 1898 mol V = 50 mL = 0 . 05 L T = 345 C + 273 . 15 = 618 . 15 K Applying the ideal gas law equation, P V = n R T P = n R T V P = (0 . 1898)(0 . 08206)(618 . 15) 0 . 05 = 192 . 554 atm 004 10.0 points What are the strongest inter molecular forces present in a liquid sample of PCl 3 ?

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Version 297 – Exam 3 – Sutcliffe – (53120) 2 1. hydrogen bonding 2. dipole-dipole correct 3. dispersion 4. covalent 5. interionic Explanation: 005 10.0 points All of the following statements, except one, are important postulates of the kinetic- molecular theory of ideal gases. Which one is not a part of this kinetic molecular theory? 1. The average kinetic energy of the molecules is inversely proportional to the ab- solute temperature. correct 2. The volume of the molecules of a gas is very small compared to the total volume in which the gas is contained. 3. The time during which a collision be- tween two molecules occurs is negligibly short compared to the time between collisions. 4. Gases consist of large numbers of particles in rapid random motion. 5. There are no attractive nor repulsive forces between the individual molecules. Explanation: The average kinetic energy of gas molecules is DIRECTLY (not indirectly) proportional to the absolute temperature. As temperature increases, so does kinetic energy.
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Exam3 - Version 297 Exam 3 Sutclie(53120 This print-out...

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