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Study Questions Chem 101 LACC MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Electromagnetic radiation with a wavelength of 525 nm appears as green light to the human eye. The energy of one photon of this light is __________ J. A) 1.04 × 10-22 B) 2.64 × C) 1.04 × 10-31 D) 3.79 × E) 3.79 × 2) Consider the molecule below. Determine the molecular geometry at each of the 2 labeled carbons. A) C1 = bent, C2 = trigonal planar B) C1 = trigonal planar, C2 = tetrahedral C) C1 = trigonal pyramidal, C2 = see-saw D) C1 = tetrahedral, C2 = linear E) C1 = trigonal planar, C2= bent 3) According to the following thermochemical equation, what mass of H2O (in g) must form in order to produce 975 kJ of energy? SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(l) A) 54.1 g B) 68.0 g C) 191 g D) 95.5 g ΔH°rxn = -184 kJ E) 102 g 4) Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction: 4 SO3(g) → 4 S(s) + 6 O2(g) ΔH°rxn = ? Given: SO2(g) → S(s) + O2(g) ΔH°rxn = +296.8 kJ 2 SO2(g) + O2(g) → 2 SO3(g) ΔH°rxn = -197.8 kJ A) -692.4 kJ B) -293.0 kJ C) -494.6 kJ D) 1583 kJ E) -791.4 kJ 5) A 21.8 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter, according to the following reaction. If the temperature rises from 25.0 to 62.3°C, determine the heat capacity of the calorimeter. The molar mass of ethanol is 46.07 g/mol. C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(g) ΔH°rxn = -1235 kJ A) 63.7 kJ/°C B) 4.99 kJ/°C C) 15.7 kJ/°C D) 5.65 kJ/°C E) 33.1 kJ/°C 6) Each of the following sets of quantum numbers is supposed to specify an orbital. Choose the one set of quantum numbers that does not contain an error. A) n = 3, l = 2, ml =+3 B) n = 4, l = 4, ml =0 C) n = 3, l = 1, ml = -2 D) n = 5, l = 3, ml =-3 E) n = 4, l = 0, ml =-1 7) Determine the shortest frequency of light required to remove an electron from a sample of Ti metal, if the binding energy of titanium is 3.14 × 103 kJ/mol. A) 6.19 x 1015 Hz B) 2.11 x 1015 Hz C) 7.87 x 1015 Hz D) 1.27 x 1015 Hz E) 4.74 x 1015 Hz 8) For hydrogen, what is the wavelength of the photon emitted when an electron drops from a 4d orbital to a 2p orbital in a hydrogen atom? The Rydberg constant is 1.097 × 10-2 nm-1. A) 2.057 × 10-3 nm B) 656.3 nm C) 486.2 nm D) 364.6 nm 9) What are the possible values of n and ml for an electron in a 4d orbital? A) n = 4 and ml = 2 B) n = 5 and ml = -2, -1, 0, +1, +2 C) n = 1, 2, 3, or 4 and ml = 2 D) n = 1, 2, 3, or 4 and ml = -2, -1, 0, +1, or +2 10) Give the ground state electron configuration for I. A) [Kr]5s24d105p6 B) [Kr]5s25d105p6 C) [Kr]5s24d105p5 D) [Kr]5s25p6 E) [Kr]4d105p6 11) Give the set of four quantum numbers that could represent the last electron added (using the Aufbau principle) to the Ne atom. A) n = 3, l = 0, ml = 1, ms = B) n = 3, l =2 , ml = 1, ms = C) n = 2, l = 1, ml = 1, ms = D) n = 3, l = 1, ml = 1, ms = + E) n = 3, l = 2, ml =1 , ms = + 12) What is the molecular geometry of TeCl4? A) tetrahedral B) seesaw C) square pyramidal D) square planar 13) What is the molecular geometry of NCl3? A) T-shaped B) tetrahedral C) trigonal pyramidal D) trigonal planar 14) Use the molecular orbital diagram shown to determine which of the following is most stable. A) F2 B) F22⁺ C) F22⁻ D) O22⁺ E) Ne22⁺ 15) Draw the Lewis structure for SF6. What is the hybridization on the S atom? A) sp3 B) sp3d2 C) sp D) sp3d E) sp2 16) How many of the following molecules contain at least one pi bond? C2H6 Cl2CO C2Cl4 SeS3 A) 1 B) 4 C) 0 D) 3 E) 2 17) Using the VSEPR model, the molecular geometry of the central atom in XeF2 is __________. A) tetrahedral B) trigonal pyramidal C) linear D) bent E) trigonal planar 18) What is the O-B-O bond angle in BO33-? A) greater than 120° B) 109.5° C) 120° D) less than 109.5° 19) How many lone pairs of electrons are on the S atom in SF4 ? A) 2 B) 1 C) 0 D) 3 20) The VSEPR model predicts the HOH bond angle in H3O+ to be A) 109.5°. B) 60°. C) 90°. D) less than 109.5° but greater than 90°. 21) Using the VSEPR model, the electron-domain geometry of the central atom in SF2 is __________. A) trigonal planar B) octahedral C) linear D) trigonal bipyramidal E) tetrahedral 22) The osmotic pressure of a solution formed by dissolving 25.0 mg of aspirin 0.250 L of water at 25°C is __________ atm. in A) 1.14 × B) 1.38 C) 0.0136 D) 13.6 E) 2.45 23) Based on the figure above, the boiling point of diethyl ether under an external pressure of is __________°C. A) 40 B) 0 C) 20 D) 10 E) 30 24) Based on the figure above, the boiling point of ethyl alcohol under an external pressure of is A) 40 B) 80 C) 70 D) 20 E) 60 25) A solution is prepared by dissolving 7.00 g of glycerin ( ) in 201 g of ethanol The freezing point of the solution is __________°C. The freezing point of pure ethanol is at 1 atm. The molal-freezing-point-depression constant ( ) for ethanol is The molar masses of glycerin and of ethanol are 92.1 g/mol and 46.1 g/mol, respectively. A) -107.9 B) 0.752 C) -115.4 D) -113.8 E) -121.3 26) At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg, respectively. Calculate the total vapor pressure over a solution of benzene and toluene with Xbenzene = 0.580. A) 131 mm Hg B) 106 mm Hg C) 121 mm Hg D) 242 mm Hg 27) The Henry's law constant for helium gas in water at 30°C is 3.70 × M/atm. When the partial pressure of helium above a sample of water is 0.650 atm, the concentration of helium in the water is __________ M. A) 1.76 × 103 B) 1.30 C) 5.69 × 10-4 D) 2.41 × 10-4 E) 3.70 × 1) D 2) B 3) C 4) D 5) C 6) D 7) C 8) C 9) B 10) C 11) C 12) B 13) C 14) D 15) B 16) D 17) C 18) C 19) B 20) D 21) E 22) C 23) A 24) D 25) C 26) A 27) D