Name: ___________________________________________________ © Keeney-Kennicutt, 2005 A1 CHEMISTRY 101 SPRING 2005 EXAM 3 FORM A SECTIONS 501-511 DR. KEENEY-KENNICUTT Directions: (1) Put your name and signature on PART 2 of the exam where indicated. (2) Sign the Aggie Code on PART 2 of this exam. (3) Each multiple choice question is actually 2 questions on your scanning sheet. If you are sure of an answer, put the same answer down for both questions for 5 pts. If you cannot decide between two answers, put one answer down for one question and the other answer down for the other question. If you get one correct you'll get half credit for 2.5 pts. If there is an ambiguous multiple choice question, use the last page to explain your answer. (4) Do NOT write on the envelope. (5) When finished, put everything in the envelope and wait to be excused. At the table, take everything out of the envelope. You can pick up the multiple choice part with the answers outside my office after the exam. (6) There are a total of 27 questions (15 actual questions). PART 1 1&2. Which of the following bonds can be classified as polar covalent? (a) H-F (b) Ca-Zn (c) N-Cl (d) Na-Br (e) C-S 3&4. In the reaction: H2SO4 + HClO4 → H3SO4+ + ClO4- the two Bronsted bases are .... (a) H2SO4 and HClO4 (b) H2SO4 and ClO4- (c) H3SO4+ and ClO4- (d) HClO4 and ClO4- (e) H2SO4 and H3SO4+ 5&6. The number of protons and electrons found in the sulfur ion that is isoelectronic with a noble gas is: (a) 16 p and 16 e- (b) 18 p and 16 e- (c) 16 p and 18 e- (d) 18 p and 17 e- (e) some other combination© Keeney-Kennicutt, 2005 A2 7&8. Arrhenius defined a base as: (a) an electron-pair donor (b) a hydroxide-ion source in water (c) an electron-pair acceptor (d) a hydrogen-ion source in water (e) a metal-ion source in water 9&10. Here is the structure for most students' friend: caffeine. Which of the following hybridization assignments is NOT correct? Beware - I did not put the lone pairs of electrons into the diagram. (a) O1 - sp2 (b) C2 - sp2 (c) C3 - sp3 (d) N4 - sp2 (e) they are all correct 11&12. Which of the following statements is CORRECT with regard to atomic or ionic size? (1) S2- < Cl- (2) Br < Br- (3) Li+ < Li (4) P < N (a) 1 and 2 (b) 3 and 4 (c) 2 and 3 (d) 2 and 4 (e) 1 and 3© Keeney-Kennicutt, 2005 A3 13&14. Which response includes only the species below that exhibit resonance? (1) NO2− (2) BF3 (3) CO2 (4) H2CO3 (a) 1 only (b) 1, 2 (c) 3 only (d) 1, 3, 4 (e) another combination 15&16. Which group has the outer electron configuration of ns2 (n-1)d1-10? (a) alkaline earths (b) transition metals (c) noble gases (d) alkali metals (e) lanthanides 17&18. According to Valence Bond Theory and Valence Shell Electron Pair Repulsion Theory, if the electronic geometry is octahedral, the hybridization must be: (a) sp (b) sp2 (c) sp3 (d) sp3d (e) sp3d2 19&20. Which of the following molecules is polar? (a) PF3 (b) BBr3 (c) SiF4 (d) BeF2 (e) SF6© Keeney-Kennicutt, 2005 A4 21&22. Which indication of relative acid strength is WRONG? (a) H2SO4 > HSO4− (b) HF < HI (c) H2SeO4 < H2SO4 (d) H2S < H2Se (e) HBrO2 > HBrO3 23&24. If 255 mL of 1.00 M HCl solution is added to 155 mL of 2.00 M NaOH, the resulting solution will be _________ M in NaCl. (a) 0.250 M (b) 1.50 M (c) 0.321 M (d) 0.622 M (e) 0.915 M© Keeney-Kennicutt, 2005 A5 CHEMISTRY 101 EXAM 3 Form A SPRING 2005 S 501-511 NAME Signature PART 2 Please read and sign: “On my honor, as an Aggie, I have neither given nor received unauthorized aid on this exam.” _______________________________________________ (24 pts) 25. (i) Draw the Lewis dot structures for the following species (2 pts each). Show all lone pairs of electrons. For the central atom, give the number of regions of high electron density (2 pts), the hybridization (2 pts), electronic geometry (2 pts), the molecular (or ionic) geometry (2 pts), and say if the species has a dipole moment or not (2 pts). (a) SeF3− (b) SeF2 SeF3− SeF2 Regions of High e- Density Hybridization Electronic Geometry Molecular Geometry Dipole Moment? (Yes or No) (6 pts) (ii) Draw a 3-dimensional representation of these 2 species using wedges and dotted lines. Show ALL lone pairs of electrons, not just the ones on the central atom. Show the bond angles. (a) SeF3− (b) SeF2 OVER ⇒© Keeney-Kennicutt, 2005 A6 26. The first ionization energy of lithium is +520 kJ/mol of atoms. (3 pts) (a) Define ionization energy in a formal way (include an equation). (2 pts) (b) What is the general trend of the first ionization energies of Group A elements with position in the periodic table? You can draw and label a diagram. 27. Here again is the structure for caffeine. (a) (2 pts) How many sigma bonds are present? _____________ (b) (2 pts) How many pi bonds are present? _____________________ (c) (1 pt) How many lone pairs of electrons are present? ____________________ (You have to look for them!)© Keeney-Kennicutt, 2005 A7 SCRAP PAPER OR COMMENTS ON EXAM CHEMISTRY 101 EXAM 3 Form A Spring 2005 S 501-511
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