PracticeExam3Key

# PracticeExam3Key - Exam 3 Petrovich CH101 Name print last...

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Exam 3 - Petrovich CH101 Name: __________________,________________ print last print first Unity ID:____________________ Page 1 # correct = _____________/ 1a. The flask shown below has a volume of 500. mL and a pressure of 0.97 atm at 27.0 ° C. How many moles of gas are contained in the flask? n = PV/RT = 0.97 * 0.5 / (0.0821 * (273.15 + 27)) n = 0.0197 = 0.020 moles -1 for bad mL to L conversion ___ 0.020 ______ moles of gas (4 pts) b. Given that the atmospheric pressure is 1.01 atm, what is the height (h) in mmHg? 1.01 atm – 0.97 atm = 0.04 atm. 0.04 atm * 760 mm Hg/atm = 30.4 mm Hg _____ 30.4 ____ mm Hg (3 pts) 2. A stoppered 5.00 liter flask contains 25.0 grams of chlorine gas. What is the molarity of the chlorine? M = mol/L = 25.0 g Cl 2 * (1 mol Cl 2 /70.9 g Cl 2 ) / 5.00 L = 0.0705 mol Cl 2 / L [Cl 2 ] = ___ 0.0705 ____ (3 pts) 3. Consider the materials below at 1 atmosphere. Place a circle around the material with the greatest interaction energy . Place a square around the material with the greatest thermal energy . (2 pts each, 4 pts total) ICE LIQUID WATER STEAM ALL ARE THE SAME 4. Describe each of the following molecules as polar or nonpolar and list all the intermolecular forces that exist in a sample of that substance. Circle ALL Intermolecular Forces Present Dipole-dipole Dispersion H Bonding Ionic (3 pts) .. H O O H Dipole-dipole Dispersion H Bonding Ionic (3 pts) S C O

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Page 2 # correct = _____________/ A B C G D E H I J K L M F 5. From the compounds below, circle the one that has the highest melting point, and put a box around the one that has the lowest melting point: (2 pts each, 4 pts total) F 2 H 2 O Kr CsI MgO SO 2 6. Will hydrogen bonding occur between molecules B and C below? (3 pts) YES NO 7. Consider the phase diagram below for Daffy Duck's Compound X, from Duck Dodgers in the 21st and a Half Century. a) What is the state of the material at 60 o Celcius and 1 atmosphere of pressure? ___ gas ______(2 pts) b) Which arrow ( H-M ) represents melting? _____ J _____ (2 pts) c) At 0.75 atmospheres of pressure, what is the melting point? _____ ~15 ______ o C (2 pts) 8. The pressure of water vapor in the atmosphere is fond to be 7.3 torr when it is 25 o C. The vapor pressure of water is 23.8 torr when it is 25 o C. What is the relative humidity? % hum = 100 * actual VP / maximum VP = 100 * 7.3 / 23.8 = 30.7% = 31% relative humidity = ____ 31 ____% (3 pts) 9. Circle the term that best describes the substances shown below: Substance Type of material NH 4 C 2 H 3 O 2 Metallic Ionic Network Covalent Molecular (3 pts) ZnS Metallic Ionic Network Covalent Molecular (3 pts) Pt Metallic Ionic Network Covalent Molecular (3 pts) H H H H H H H H .
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## This test prep was uploaded on 03/29/2008 for the course CH 101 taught by Professor Bigham during the Spring '08 term at N.C. State.

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PracticeExam3Key - Exam 3 Petrovich CH101 Name print last...

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