Section CHEM105 004 Test 3 Thursday December 4, 2008
Name: _______________________
Answer as many of the following questions from any section as you would like. Questions from the Games! And Fiesta! Sections have higher individual point values than the ones from the Fun! Section, but you probably already knew that. You have 70 minutes to take this exam and may use the periodic table given to you and your scientific calculator. Please draw a box around your answers. All work must be shown or no credit will be given. Section 1: Fun! (4 points each)
Hurray!
1) Which of the following statements is/are CORRECT? 1. The overlap between an s orbital and a p orbital is called a pi-bond. 2. The overlap of two s orbitals in H2 is called a sigma bond. 3. HF is formed from the overlap of a hydrogen 1s orbital with a fluorine 2s orbital. a) 1 only b) 2 only c) 3 only d) 2 and 3 e) 1, 2, and 3 Answer: b 2) What is the hybridization of either carbon atom in acetylene, C2H2? a) sp b) sp2 c) sp3 d) sp3d Answer: a 3) What is the hybridization of the nitrogen atom in NCl3? a) sp b) sp2 c) sp3 d) sp3d Answer: c 4) What is the hybridization of the central nitrogen atom in nitrite ion, NO2-? a) sp b) sp2 c) sp3 d) sp3d e) sp3d2 Answer: b 5) Which of the underlined atoms (C1, C2, N, and O) are sp2 hybridized? .. OH H a) C1 and C2 H .. b) C1, N, and O .O C1 H . C C2 c) N and O H C C C C H d) O and C2 C C e) O only NH2 H
H H
e) sp3d2
e) sp3d2
Answer: a 6) What is the name of the following compound? a) 3-ethyl-5,6-dimethylheptane CH3 b) 2,3,5-ethylmethylethylheptane c) 3-ethyldecane CH3 CH CH CH2 d) 2,3-dimethyl-3-ethylheptane e) 3,5,6-trimethylheptane CH3 Answer: a 7) What is the name of the following compound? a) trans-1-methyl-1-butene H b) cis-1-methyl-1-butene c) trans-2-pentene C d) trans-3-pentene CH3 e) trans-1-methyl-2-ethylethylene Answer: c 8) A saturated hydrocarbon is a) a hydrocarbon that contains oxygen. b) a compound in which all carbon atoms have four single bonds. c) a compound in which one or more carbon atoms have double or triple bonds. d) a hydrocarbon that is dissolved in water. e) a cycloalkane with five or more carbons. Answer: b 9) Putrescine and cadaverine are two compounds associated with decaying flesh or bad breath. These compounds belong to a class of molecules called ________. a) ethers b) amines c) ketones d) esters e) carboxylic acids Answer: b
CH C2H5
CH2
CH3
CH2 C H
CH3
10) Which of the structures below has the common name m-dichlorobenzene (where mis meta)? Cl Cl Cl Cl Cl Cl Cl Cl d) e)
Cl a) Answer: c 11) Which of the following represents the greatest pressure? a) 1.0 atm b) 1.0 bar c) 1.0 mm Hg d) 1.0 kPa e) 1.0 psi Answer: a b) c)
12) If the volume of a confined gas is reduced to the original volume while its temperature remains constant, what change will be observed? a) The pressure of the gas will increase to twice its original value. b) The pressure of the gas will remain unchanged. c) The density of the gas will decrease to its original value. d) The pressure of the gas will decrease to its original value. e) The average velocity of the molecules will double. Answer: a 13) Which of the following relationships is/are CORRECT for gases? 1. The moles of a gas is inversely proportional to its volume (at constant pressure). 2. The volume of a gas is inversely proportional to its temperature in kelvin (at constant pressure). 3. The pressure of a gas is directly proportional to its temperature in kelvin (at constant volume). a) 1 only b) 2 only c) 3 only d) 1 and 2 e) 2 and 3 Answer: c 14) Which of the following statements are postulates of the kinetic-molecular theory of gases? 1. Gas particles are in constant, random motion.
2. The distance between gas particles is large in comparison to their size. 3. The kinetic energy of gas particles is inversely proportional to the kelvin temperature. a) 1 only b) 2 only c) 3 only d) 1 and 2 e) 1, 2, and 3 Answer: d 15) Non-ideal behavior for a gas is most likely to be observed under conditions of a) high temperature and low pressure. b) high temperature and high pressure. c) low temperature and low pressure. d) standard temperature and pressure. e) low temperature and high pressure. Answer: e 16) Which of the following statements concerning the attraction of ions to polar molecules is/are CORRECT? 1. The energy of attraction an between ion and a polar molecule is directly proportional to the square of the distance between the center of the ion and the oppositely charged pole of the dipole. 2. The higher the ion charge, the greater the attraction between the ion and a polar molecule. 3. The greater the magnitude of the dipole, the greater the attraction between the ion and a polar molecule. a) 1 only b) 2 only c) 3 only d) 2 and 3 e) 1, 2, and 3 Answer: d 17) Hydrogen bonding is present in all of the following molecular solids EXCEPT: a) H2SO4 Answer: c 18) Which intermolecular force or bond is responsible for the density of H2O(s) being less than that of H2O()? a) London dispersion forces b) hydrogen bonding c) ionic bonding d) covalent bonding e) dipole/induced dipole forces b) NH3 c) PH3 d) HF e) H2O2
Answer: b 19) Which of the following statements concerning intermolecular forces is/are CORRECT? 1. Dipole-dipole attractions occur in all molecules that contain polar bonds, regardless of whether the molecule has a dipole. 2. Hydrogen bonding occurs in all molecules containing both oxygen and hydrogen atoms. 3. Induced dipole/induced dipole forces exist in all molecular solids. a) 1 only b) 2 only c) 3 only d) 1 and 2 e) 1, 2, and 3 Answer: c 20) What intermolecular force or bond is primarily responsible for the solubility of carbon dioxide (CO2) in water? a) dipole/dipole force b) hydrogen bonding c) dipole/induced dipole force d) hydrogen bonding-dipole force e) ion-induced dipole force Answer: c
Section 2: Games! (5 points each)
Awwww, yeah!
1) One product of the combustion of ethane, C2H6, is carbon dioxide. What change in hybridization of the carbon occurs in this reaction? a) sp3 to sp2 b) sp3 to sp c) sp2 to sp3 d) sp2 to sp3d2 e) sp2 to sp Answer: b
2) What is the molecular geometry around a central atom that is sp2 hybridized, has three sigma bonds, and one pi bond? a) trigonal-planar b) trigonal-pyramidal c) bent d) T-shaped e) tetrahedral Answer: a
3) Propane, C3H8, reacts with excess oxygen to produce carbon dioxide gas and water. What volume of CO2, measured at 27.2 C and 0.918 atm is produced from the reaction of 10.1 g C3H8 with excess oxygen? (R = 0.08206 Latm/molK) a) 0.557 L b) 0.687 L c) 1.67 L d) 6.15 L e) 18.5 L Answer: e
4) Carbon monoxide reacts with oxygen to form carbon dioxide. 2 CO(g) + O2(g) 2 CO2(g) In a 1.00 L flask, 3.40 atm of CO reacts with 2.60 atm of O2. Assuming that the temperature remains constant, what is the final pressure in the flask? a) 0.80 atm b) 2.60 atm c) 3.40 atm d) 4.30 atm e) 6.00 atm Answer: d
5) At 506 K and 2.05 atm, what...