Hour Test 2 (canary) Name__________________________ CHM 1045 (Dr. Light) Soc.Sec.Num._____________________ March 8, 1996 8:00 am Recitation Section_______ This exam consists of 4 pages. Make sure you have one of each. Print your name at the top of each page now. The fifth page contains some thermochemical data and a periodic chart. You may tear this sheet off and use it for reference. A blank scratch sheet will also be provided. These pages should not be turned in. Show your work on calculations, including units, and give answers in the correct units and appropriate number of significant figures. In problems involving molecular and formula weights, you may use values rounded to the nearest 0.1 amu. If anything confuses you or is not clear, raise your hand and ask! (6) 1. The specific heat of Al(s) is 0.90 J/g-K. How much heat would be required to raise the temperature of 1.5 moles of Al from 25.0 oC to 210.0 oC? 2. A 3.60 g sample of octane (C8H18) was burned in a calorimeter whose total heat capacity is 23.32 kJ/oC. The temperature of the calorimeter increased from 21.36oC to 28.78oC. (2) (a) Write the balanced equation for the reaction. (6) (b) What is the heat of combustion per gram of octane? (4) (c) What is the heat of combustion per mole of octane? (10)3. Use the heats of formation data on the last page to calculate þH for the following reaction. CaCO3(s) -----> CaO(s) + CO2(g) (10)4. Use the heats of combustion data on the last page to calculate the þH for the following reaction. (Note: heats of combustion of H2O and CO2 are zero, since these compounds don't react with oxygen). C2H4(g) + H2O(l) -----> C2H5OH(l) (10)5. Calculate the þH for the following reaction, which represents the ionization potential of Mg(g), from the heats of formation data on the last page. Mg(g) -----> Mg+(g) (6) 6. Calculate both the wavelength and energy of a photon of radio waves carrying the signal for WFSU-FM at 88.9 MHz. (8) 7. Calculate the frequency of a photon of light emitted by a hydrogen atom in which the electron drops from the third Bohr orbit to the first Bohr orbit. (4) 8. Give the symbol for the atoms with the following electron configurations. [Ne]3s23p5 [He]2s2 [Ar]4s23d6 [Kr]5s (4) 9. Give the electron configuration for the following atoms or ions. Ni As Cr+3 Se-2 (6) 10. Identify the orbital occupied by an electron with the following sets of quantum numbers. If the set is not an allowed set of quantum numbers, write none in the space. Orbital Quantum numbers ______ n=2 l=1 m=-1 ms=+1/2 ______ n=3 l=0 m=0 ms=-1/2 ______ n=1 l=2 m=0 ms=+1/2 (4) 11. Circle the smallest and put an X through the largest atom or ion in each of the following lists. (a) K Si Mg O (b) Na+1 Mg2+ O2- Al+3 (4) 12. For each of the following sets of atoms, circle the atom with the lowest ionization energy, and put an X through the one with the largest ionization energy. (a) K Ga Br Kr (b) F Br Cl I (6) 13. In the Born-Haber cycle used for calculating the lattice energy of NaCl, put an x by each of the following processes which is exothermic (i.e., proceeds with a negative þH). ____ ionization energy of sodium ____ electron affinity of chlorine ____ heat of formation of NaCl (s) (10)14. Complete and balance the following equations. MgO + H2O -----> Ca + H2O -----> Li + H2 -----> SO3 + H2O -----> Li2O + HCl -----> The following tables of data may be useful to you. Physical constants: c = 3.00 x 108 ms-1;h = 6.63 x 10-34 J-s; RH = 2.18 x 10-18 J þH of fusion of ice = 6.008 kJ/mol; þH of vaporization of water = 40.67 kJ/mol; Specific heat of ice = 2.092 J/g-K; Specific heat of water = 4.184 J/g-K; Heats of Formation: þHfo CaCO3(s) = -1207.1 kJ/mol þHfo CaO(s) = - 635.5 kJ/mol þHfo CO2(g) = - 393.5 kJ/mol þHfo CO(g) = - 110.5 kJ/mol þHfo CH3OH(l) = - 238.6 kJ/mol þHfo Mg(g) = 147.1 kJ/mol þHfo Mg+(g) = 885.1 kJ/mol þHfo Mg2+(g) = 2335.1 kJ/mol þHfo H2O(l) = - 285.8 kJ/mol þHfo H2O(g) = - 241.8 kJ/mol þHfo C2H4(g) = 52.30 kJ/mol þHfo C2H5OH(l) = - 277.7 kJ/mol þHfo C2H2(g) = 226.7 kJ/mol þHfo C2H6(g) = - 84.68 kJ/mol þHfo C6H6(l) = 49.0 kJ/mol þHfo C4H10(g) = - 124.73 kJ/mol þHfo MgO(s) = - 601.8 kJ/mol þHfo LiCl(s) = - 408.3 kJ/mol þHfo Li(g) = 159.3 kJ/mol þHfo Li+(g) = 685.7 kJ/mol þHfo Cl(g) = 121.7 kJ/mol þHfo Cl-(g) = - 227 kJ/mol þHfo F(g) = 80.0 kJ/mol þHfo F-(g) = - 252 kJ/mol Heats of Combustion (H2O(l) as product): þHcomb C(s) = -393.5 kJ/mol þHcomb CO(g) = -283.0 kJ/mol þHcomb CH4(g) = -890 kJ/mol þHcomb H2(g) = -285.9 kJ/mol þHcomb C3H8(g) = -2220 kJ/mol þHcomb C6H6(l) = -3267 kJ/mol þHcomb CH3OH(l) = -726.5 kJ/mol þHcomb C2H5OH(l) = -1366.7 kJ/mol þHcomb C2H4(g) = -1410.9 kJ/mol þHcomb C2H2(g) = -1299.6 kJ/mol þHcomb C2H6(g) = -1559.7 kJ/mol þHcomb C6H12O6(s)= -2816 kJ/mol