Name _____Mr. Perfect________________________________ Date __F 14_______ 1. If the n quantum number of an atomic orbital is equal to 2, what are the possible values of l ? What are the possible values of ml if the quantum number l is equal to 3? (5 pts) l ranges from 0 to n-1 ml 0, 1 -3, -2, -1, 0, 1, 2, 3 2. Give the notation (using letter designations for l ) for the sub-shells denoted by the following quantum numbers. (10 pts) a) n = 2 , l = 0 b) n = 3 , l = 2 2s c) n = 4 , l = 3 3d 4f d) n = 1 , l = 0 1s 3. Write both the electron configurations and the orbital diagrams for the following elements in their ground states. Also, state if the element is paramagnetic or diamagnetic. (20 pts) a) 35Br [Ar] 4s23d104p5 [Ar] [↑↓] [↑↓][↑↓][↑↓][↑↓][↑↓] [↑↓][↑↓][↑ ] 4s 3d 4p Paramagnetic b) 4Be 1s22s2 [↑↓] [↑↓] 1s 2s Diamagnetic c) 14Si [Ne] 3s23p2 [Ne] [↑↓] [↑ ][↑ ][ ] 3s 3p Paramagnetic d) 10Ne 1s22s22p6 [↑↓] [↑↓] [↑↓][↑↓][↑↓] 1s 2s 2p Diamagnetic Chemistry 101 Exam 2 Name _____Mr. Perfect________________________________ Date __F 14_______ 4. Use the Rydberg equation to calculate the wavelength (in nm) of a photon when a hydrogen atom undergoes a transition from n = 3 to n = 5. Clearly state if light was absorbed or emitted in this transition. Would this transition occur in the infrared or ultraviolet region of the electromagnetic spectrum? R = 1.0967 x 107 m-1 (15 pts) 1 R( 1 1 2) 2 n1 n2 n2 > n1 ( ( ) ) Light was absorbed 5. If ΔE for an electronic transition in a hydrogen atom is –3.029 x 10-19 J, find nf if ni = 3. RH = 2.179 x 10-18 J (10 pts) E RH ( 1 1 2) 2 n f ni ( ) ( √ Chemistry 101 Exam 2 ) Name _____Mr. Perfect________________________________ Date __F 14_______ 6. An experiment shows a 113 mL gas sample has a mass of 0.171 g at a pressure of 721 mmHg and a temperature of 32 °C. Find the molar mass of the gas. (10 pts) R = 0.0821 L atm/mol K PV = nRT T = 32 + 273 = 305 K P = 721 mmHg x 1 atm/760 mmHg = 0.9486 atm )( ) ( ( )( ( ) ) What volume will one mole of the above gas mixture occupy at STP? (5 pts) STP (Standard Temperature and Pressure) 1 atm and 0 °C (273 K) ( )( )( ) 7. Mothballs are composed primarily of the hydrocarbon naphthalene (C10H8). When 1.025 g of naphthalene is burned in a bomb calorimeter, the temperature of the calorimeter rises from 24.25 °C to 32.33 °C. Find ΔErxn (kJ/mol) for the combustion of naphthalene. The heat capacity of the calorimeter is 5.86 kJ/ °C. (10 pts) Qcal = Ccal ΔT Qcal = 5.86 kJ/°C(32.33 °C – 24.25 °C) = 47.3 kJ Qcal = - Qrxn Qrxn = -47.3 kJ 1.025 g x 1mol/128g = 8.01 x 10-3 mol Chemistry 101 Exam 2 Name _____Mr. Perfect________________________________ Date __F 14_______ 8. Given the following data: Reverse 2O3(g) → 3O2(g) ΔH° = -427 kJ 2x NO(g) + O3(g) → NO2(g) + O2(g) ; ΔH° = -199 kJ Reverse O2(g) → 2O(g) ΔH° = 495 kJ ; ; Calculate the ΔH° for the following reaction: (10 pts) NO(g) + O(g) → NO2(g) 3O2(g) → 2O3(g) ΔH° = ? 427 kJ 2NO(g) + 2O3(g) → 2NO2(g) + 2O2(g) -398 kJ 2O(g) → O2(g) -495 kJ 2NO(g) + 2O(g) → 2NO2(g) -466 kJ NO(g) + O(g) → NO2(g) ΔH° = -233 kJ 9. The first ionization energies of As and Se are 0.947 MJ/mol for As and 0.941 MJ/mol for Se. Explain this result using orbital diagrams. (5 pts) As [Ar] [↑↓] [↑↓][↑↓][↑↓][↑↓][↑↓] [↑ ][ ↑ ][↑ ] 4s 3d 4p Se [Ar] [↑↓] [↑↓][↑↓][↑↓][↑↓][↑↓] [↑↓][↑ ][↑ ] 4s 3d 4p The periodic trend would predict Se to have a higher ionization energy than As but the reverse is true. This is due to the electron-electron repulsion in the 4p orbital of Se. 10. (Extra Credit) A system releases 415 kJ of heat and does 125 kJ of work on the surroundings. What is the change in internal energy of the system? (5 pts) ΔE = q + w = (-415 kJ) + (-125 kJ) = -540 kJ Chemistry 101 Exam 2

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