Midterm Exam Summer 2023 CHEM1100 (2)

1. Chemical energy is a. the kinetic energy resulting from violent decomposition of energetic chemicals. b. the heat energy associated with combustion reactions. c. the electrical energy produced by fuel cells. d. the potential energy which resides in chemical bonds. e. the energy living plants receive from solar radiation. 2. The standard enthalpy of reaction,  H ° rxn , for the reaction, CaO( s ) + SO 3 ( g )  CaSO 4 ( s ) is -401.5 kJ mol -1 . Determine the value of  U ° rxn for this reaction. a. -362.2 kJ mol -1 b. - 399.0 kJ mol -1 c. -404.0 kJ mol -1 d. -2880 kJ mol -1 e. +2077 kJ mol -1 3. A 350.0 gram sample of copper is initially at 25.0 ° C. It absorbs 12.50 kJ of heat from its surroundings. What is its final temperature, to the nearest tenth of a degree? (specific heat = 0.387 J g -1 ° C -1 for copper) a. 38.8 ° C b. 67.2 ° C c. 92.2 ° C d. 117.3 ° C e. 156.7 ° C 4. An endothermic reaction is one in which there is a. a positive value for the work done by the system (w > 0 joules) b. a negative value for the work done by the system (w < 0 joules) c. a negative value for ΔH (ΔH < 0 joules) d. a positive value for ΔH (ΔH > 0 joules) e. a negative value for ΔE (ΔE > 0 joules) 5. A closed, uninsulated system fitted with a movable piston was assembled in which no matter is exchanged with the surroundings. Introduction of 430 J of heat caused the system to expand, doing 238 J of work in the process against a constant pressure of 101 kPa (kilopascals). What is the value of ΔU for this process? a. (430 + 238) joules b. (430 - 238) joules c. (238 - 430) joules d. 430 joules e. (-238 - 430) joules

6. Given the reaction, 5A + 3B → 7C + 3D, and some standard enthalpies of formation, A: -15.7 kJ mol -1 B: -86.4 kJ mol -1 C: -52.7 kJ mol -1 D: -71.6 kJ mol -1 What is the standard enthalpy of reaction, in kJ for the reaction shown? a. +26.6 kJ b. -53.6 kJ c. -198.8 kJ d. - 246.0 kJ e. -413.5 kJ 7. The thermochemical equation which is associated with the standard enthalpy of formation, for urea, CO(NH 2 ) 2 ( s ), is a. CO( g ) + 2 NH 3 ( g ) → CO(NH 2 ) 2 ( s ) + H 2 ( g ) b. CO( g ) + 2 H 2 ( g ) + N 2 ( g ) → CO(NH 2 ) 2 ( s ) c. C( s ) + O( g ) + N 2 ( g ) + 2 H 2 ( g ) → CO(NH 2 ) 2 ( s ) d. C( s ) + ½ O 2 ( g ) + N 2 ( g ) + 2 H 2 ( g ) → CO(NH 2 ) 2 ( s ) e. C( s ) + ½ O 2 ( g ) + 2 NH 2 ( g ) → CO(NH 2 ) 2 ( s ) 8. Use these reactions and standard enthalpies, ΔH° 2 ZbO( s ) + ½ O 2 ( g ) → Zb 2 O 3 ( s ) -128.0 kJ ZbO( s ) + ½ O 2 ( g ) → ZbO 2 ( s ) -380.0 kJ 2 ZbO( s ) + 3/2 O 2 ( g ) → Zb 2 O 5 ( s ) -344.5 kJ To find the value for Zb 2 O 3 ( s ) + O 2 ( g ) → Zb 2 O 5 ( s ) ______ 9. 600.0 mL of 0.240 M perchloric acid, HClO 4 ( aq ) was added to a high quality constant- pressure calorimeter containing 400.0 mL of 0.300 M KOH( aq ). Both solutions have a density of 1.000 g mL -1 and a specific heat of 4.184 J g -1 ° C -1 . The calorimeter had a heat capacity of 950.0 J ° C -1 . The temperature of the entire system rose from 25.30 ° C to 26.59 ° C. Calculate the heat of reaction, in kJ, per mole of KOH( aq ). ______

14. "No two electrons in the same atom can have all their quantum numbers the same." This statement is based on the work of a. Louis de Broglie b. Werner von Heisenberg c. Albert Einstein d. Wolfgang Pauli e. Erwin Schrödinger 15. Given the following sets of quantum numbers for n, l, m l , and m s , which one of these sets is not possible for an electron in an atom? n l m l m s a. 3 2 2 -½ b. 3 1 -1 ½ c. 4 3 2 ½ d. 4 4 - 3 - ½ e. 5 2 -2 ½ 16. Which placement of electrons is never encountered in the ground state configuration of an atom? a. 3d 4 with 4 unpaired electrons b. 3d 7 with 3 unpaired electrons c. 3p 1 with 1 unpaired electron d. 3d 9 with 4 unpaired electron e. 4f 7 with 7 unpaired electrons 17. Which configuration represents a situation that cannot exist for a ground state or for an excited state (because it violates the Pauli principle)? a. [Ar] 4s 2 3d 10 4p 5 b. [Xe] 5s 2 4d 10 5p 4 c. [Rn] 7s 2 5f 8 d. [Kr] 5s 1 4d 6 e. [Ne] 6s 1

18. A possible set of quantum numbers for an electron in the partially filled subshell in a gallium atom in its ground state configuration would be n l m l m s a. 3 1 0 -½ b. 3 1 1 ½ c. 4 0 0 -½ d. 4 1 0 ½ e. 4 2 1 ½ 19. Based on its expected electron configuration, element Z = 120 a. should be an inert gas element. b. should have two unpaired electrons. c. should be an alkali metal. d. should be an alkaline earth element. e. should have four unpaired electrons. 20.Which atom in the set: Ba, Cr, N, Sn, Mg, Sn, Se would you expect to have the largest atomic radius? 21. Kevin is working on a summer project in which he is using a tunable dye laser. At first, he used radiation on a wavelength of 488.5 nm. After two weeks, his research advisor told him to increase the energy by another 55.0 kJ per mole and repeat the radiation effect tests. What wavelength should he then use? _______ 22. Which ion has a noble gas configuration? a. Fe 3+ b. Sn 2+ c. Ni 2+ d. Ti 4+ e. Cr 3+