Chem 177 Exam II: Summer 2008, Exams of Chemistry

Download Chem 177 Exam II: Summer 2008 and more Exams Chemistry in PDF only on Docsity! Prof. Joe Burnett Summer 2008 This exam consists of 24 questions on 9 pages. CHEM 177 Hour Exam II June 23, 2008 Name______________________ Recitation Instructor Circle one: Ji Chad GRADING PAGES Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 TOTAL POINTS 26 pts 20 pts 22 pts 12 pts 14 pts 7 pts 101 pts SCORE ________ ________ ________ ________ ________ ________ Note: The method that you use in solving questions must be clearly shown to receive full credit. Questions are written on both sides of each page. A periodic table is on the last page of the exam. This may be removed and used for scratch paper and reference. Do not put answers on the periodic table page – it will not be graded. 2 1. (2 pts) Which one of the following is a weak acid? A. HCl B. HNO3 C. HF D. HClO3 E. HI 2. (2 pts) What is the formula of hydrobromic acid? ______________________ 3. (4 pts) Which one of the following is NOT a valid set of quantum numbers? A. n = 3, l = 0, ml = 0, ms = +1/2 B. n = 3, l = 2, ml = –2, ms = –1/2 C. n = 4, l = 3, ml = 2, ms = +1/2 D. n = 3, l = 3, ml = 0, ms = –1/2 4. (6 pts) Draw all 3p orbitals in a given atom; draw one on each axis using only as many axes as needed. Label the orbitals appropriately and indicate any planar nodes. Points will be deducted for having too many or too few orbitals. Note that the number of axes is not related to the number of 3p orbitals. 5. (8 pts) Fill in the following table. You may use shorthand notation for electronic configurations. Atom electronic configuration # of core electrons # of valence electrons # of unpaired electrons Fe (Z = 26) Sb (Z = 51) 6. (4 pts) When 10.0 mL of 0.10 Molar KCl is combined with 10.0 mL of 0.20 Molar K3PO4, the molar concentrations of K+, Cl–, and PO43– are ___, ___, and ___, respectively. A. 0.10; 0.10; 0.20 B. 0.35; 0.050; 0.10 C. 0.35; 0.10; 0.10 D. 0.50; 0.10; 0.20 E. 0.15; 0.050; 0.10 F. 0.30; 0.0.10; 0.20 z x y z x y z x y z x y 5 16. (6 pts) 1.922 g of methanol (CH3OH, molar mass 32.05 g/mol) was burned in a constant-volume (bomb) calorimeter. The temperature of the calorimeter increased by 4.20oC. The heat capacity of the calorimeter is 10.4 kJ/oC. Calculate ΔE for the following reaction in kJ. For full credit, show all work, use units, and report your answers to the correct number of significant figures. 2 CH3OH(l) + 3 O2(g) !"! 4 H2O(l) + 2 CO2(g) 17. (6 pts) Using enthalpies of formation, calculate ΔHo for the following. For full credit, show all work, use units, and report your answers to the correct number of significant figures. 2 CH3OH(l) + 3 O2(g) !"! 4 H2O(l) + 2 CO2(g) 6 18. (4 pts) Consider the reaction: 2 H2(g) + O2(g) !"! 2 H2O(l) ΔH = –571.6 kJ When the reaction is performed at standard pressure and temperature, 7.4 kJ of work are performed by the surroundings on the reaction (system). What is ΔE for the reaction in kJ? For full credit show all work, use units, and report your answer to the correct number of significant figures. 19. (6 pts) Photodissociation of water has been suggested as a source of hydrogen for fuel: H2O(l) + photon !"! H2(g) + 1 2 O2(g) A minimum photon energy of 4.749 × 10–19 J is needed to decompose a single water molecule. What is the maximum wavelength in nm of light needed to dissociate a single water molecule? For full credit show all work, use units, and report your answer to the correct number of significant figures. 20. (2 pts) Circle the atom with the smallest radius and underline the atom with the largest radius. Ne Kr K N 21. (2 pts) Circle the atom with the smallest first ionization energy and underline the atom with the largest first ionization energy. Ne Kr K N 7 22. (3 pts) Identify the following atoms/ions as S2–, Ar, or Ca2+. 23. (2 pts) Rank the following atoms in order of increasing effective nuclear charge (Zeff) experienced by the valence electrons: K Ga Kr __________ __________ __________ lowest Zeff largest Zeff 24. (2 pts) True or False __________________ Bonding radii are shorter than are nonbonding radii.