Form Code X NAME. CHM 2045, Fall 2016, Exam 2 Review Packet (UF Teaching Center)

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1 Form Code X NAME CHM 2045, Fall 2016, Exam 2 Review Packet (UF Teaching Center) Exam Packet Instructions: Do your best and don t be anxious. Read the question, re-read the question, write down all given or valuable information, and write down what you want to find. As on all graded events, the loving of moles applies. 1. If you dropped a 1 gram chunk of either iron (heat capacity = J/gK) or gold (heat capacity = J/gk) at 100 C into 1 gram of water at 25 C, which metal would change the water temperature most and is the water temperature change endothermic or exothermic? (1) Iron, water temperature change is exothermic (2) Iron, water temperature change is endothermic (3) Gold, water temperature change is exothermic (4) Gold, water temperature change is endothermic (5) Both are the same, water change is endothermic 2. The work function of an element is the energy required to remove an electron from the surface of the solid element. The work function for chromium is kj/mol. What is the maximum wavelength (in nm) of light that can remove one electron from an atom of the surface of chromium metal? (1) 428 nm (2) 710 nm (3) 339 nm (4) 912 nm (5) 183 nm

2 3. Select the false statement below (1) Fe has 2 outer electrons, 8 valence electrons, and 18 core electrons (2) Fe 2+ is more paramagnetic than Fe 3+ (3) Fe 3+ is isoelectronic with Mn 2+ (4) none of these ions (Fe 2+, Fe 3+, Mn 2+ ) have any electrons in the 4s subshell (5) Fe 3+ is predicted to be a stronger potential oxidizing agent than Fe Rank the following five ions in order of increasing ionic radius: Rb +, In 3+, Al 3+, Sr 2+, Ga 3+ (1) In3+ < Sr2+ < Rb+ < Al3+ < Ga3+ (2) Rb+ < In3+< Al3+ < Sr2+ < Ga3+ (3) Ga3+ < In3+ < Al3+ < Sr2+ < Rb+ (4) Al3+ < Ga3+ < In3+ < Sr2+ < Rb+ (5) Al3+ < Ga3+ < In3+ < Rb+ < Sr2+

3 5. The overall reaction in the commercial heat pack can be represented as 4Fe(s) + 3O2(g) 2Fe2O3(s) H = 1652 kj How much heat is released when 26.0 g Fe and 4.60 g O2 are reacted? 1) kj/mol 2) kj/mol 3) kj/mol 4) kj/mol 5) -826 kj/mol 6. Use the following information to find ΔH f of gaseous HCl: N2(g) + 3 H2(g) 2 NH3(g) ΔH rxn = 91.8 kj N2(g) + 4 H2(g) + Cl2(g) 2 NH4Cl(s) ΔH rxn = kj NH3(g) + HCl(g) NH4Cl(s) ΔH rxn = kj 1) kj/mol 2) kj/mol 3) kj/mol 4) kj/mol 5) kj/mol

4 7. Enormous numbers of microwave photons are needed to warm household samples. A bowl of soup containing 400g of water is heated in a microwave oven from 20.0 C to 98.0 C using radiation with wavelength 122 mm. Assuming that the specific heat capacity of the soup is the same as that of water (4.184 J/g C) and no heat loss to the bowl, which choice is closest to the number of photons absorbed? 1) 4.0*10-6 2) 8.0* ) 4.0*10 6 4) 8.0* ) None of the above 8. Select the true statement: (1) Photons of green light have greater energy than photons of red light (2) Light emitted by an n = 4 to n = 2 transition will have greater energy than light from an n = 3 to n = 1 transition (3) The energy of a photon is inversely related to its frequency and directly related to its wavelength (4) There are three angular momentum subshells associated with the n = 3 shell (5) In accordance with Pauli s Principle, a ground-state phosphorus atom contains three unpaired electrons in its 3p subshell

5 9. Which choice contains a possible set of quantum numbers (n, l, ml, ms) for the first electron removed from a ground-state vanadium atom? (1) 4, 0, 0, +½ (2) 4, 1, 0, ½ (3) 3, 2, 0, +½ (4) 3, 1, 1, +½ (5) 4, 2, 2, ½ 10. Which of the following transitions in a hydrogen atom would absorb the longest wavelength photon? (1) n = 1 to n = 2 (2) n = 6 to n = 5 (3) n = 2 to n = 1 (4) n = 2 to n = 3 (5) n = 5 to n = 6

6 11. The electronic transitions responsible for the Balmer lines in the H atom terminate on n = 2. What is the n value for the upper level if the wavelength emitted is 410 nm? (1) n = 7 (2) n = 6 (3) n = 5 (4) n = 4 (5) n = Which of the following is true regarding Hydrofluoric Acid? I) Hydrofluoric Acid s bond requires a high amount of energy to break II) Hydrofluoric Acid is a weak acid due to Fluorine s high electronegativity III) Hydrofluoric Acid has a short bond length with H IV) Hydrofluoric Acid bond is polar covalent V) All of the above

7 13. When 14.2 g KBr is dissolved in g of water in a coffee-cup calorimeter (of negligible heat capacity), the temperature drops from ºC to ºC. If the solution has a specific heat capacity which is essentially the same as H2O(l), J/g C, the enthalpy change per gram of KBr dissolved is closest to (1) 28.6 J/g (2) 162 J/g (3) 326 J/g (4) 2.63 x 10 3 J/g (5) 185 J/g 14. Which of the following processes is endothermic? 1) Li + (g) + e Li(g) 2) Br(g) + e Br (g) 3) Li + (g) + Br (g) LiBr(s) 4) CH3CH2CH2OH(g) + 2O2(g) CO2(g) + 2H2O(g) 5) ½Br2(g) Br(g)

8 15. Given how the following elements are ranked, the elements could be considered being listed in accordance to. I) Increasing electronegativity II) Decreasing Ionization Energy III) Decreasing electronegativity IV) Increasing Atomic Size V) Increasing Ionization Energy VI) Decreasing Atomic Size Cs < Ba < Si < P< C < O < F 1) I, II, V only 2) I, V, VI only 3) II, III, VI only 4) I, IV, V 5) None of the Above 16. In an analytical chemistry lab, Jack shines a laser tuned at a certain wavelength upon a cuvette. The cuvette contains a certain solution with a huge molar absorptivity at this wavelength. After doing the calculations, he finds out that 3.54*10 6 photons were produced and the overall energy produced by the photons was approximately 1.001*10-12 Joules. What was the laser s wavelength? 1) 282 nm 2) 700 nm 3) 635 nm 4) 354 nm 5) 5.61*10-35 nm

9 GOOD LUCK and SMILE ON THE EXAM!!! -Broward Teaching Center

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