PAST EXAMS - EXAM 2 - SPRING 07 - WORKED SOLUTIONS

PAST EXAMS - EXAM 2 - SPRING 07 - WORKED SOLUTIONS -...

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Solutions - Exam 2 - Form Code A - Sprin~ 2007 1. Only D (answer 4) is endothermic (heat is required to melt ice to form liquid water). The rest of the reactionslstate-changes are exothermic (they give off heat). 2. Use the Rydberg Equation: lA = R [(l/nf2) - (l/ni2)] 11 h = (1.097 x lo7 m-')[(114~) - (1/6*)] = 3.809 x 10' m-' h = 1 13.809 x lo5 m-' = 2.626 x m = 2626 nm (answer 5) 3. Answer 5 is correct: the photon emitted from the transition of an electron from n = 6 to n = 5 has the least energy of all the transition options given in the question, because the energy level difference (the AE) between these two levels is less than that between any of the other levels - the further away from the nucleus of the hydrogen atom, the closer the energy levels become, and the AE between them becomes closer. 4. Answer 4 (NZF4) is the only molecule that is not planar. /-\ - I' 5. Answer 5 (SF4) is the only molecule that is not tetrahedral. \- - 6, Bond polarity is based on the difference in electronegativity (AEN) between the tw- bound atoms. So, N-Br has a AEN of 0, N-0 has a AEN of 0.4, P-Cl has a AEN of 1.0, and C-C has a AEiN of 0. Therefore P-Cl (answer 4) is the most polar bond. r2 I) 7. The sulfur-t~~pitrogen bond in F3SN is a triple bond (answer 3). r~*.dl 7; @ '37 krs+ Ed w/.lbrmrl &wy = 0 I J ,I ( fid (more s+&bb) . -7 "PL~~~J<L 044. :I=: X : .# F: I/ , 8. Molecular polarity is based on the net summation of dipole moments of any polar bonds within the molecule - that is, if a molecule has a net dipole moment, it is polar. All of the molecules given have bond dipole moments within their symmetrical molecules that cancel each other, except for H202 (answer 2) which is a nonlinear nonsymmetrical molecule and therefore has a net dipole moment and therefore is polar.
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This note was uploaded on 05/31/2008 for the course CHM 2045 taught by Professor Mitchell during the Spring '07 term at University of Florida.

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PAST EXAMS - EXAM 2 - SPRING 07 - WORKED SOLUTIONS -...

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