TINA AKINYI CHEM 177 EXAM 3 REVIEW 4/12/15

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1 TINA AKINYI CHEM 177 EXAM 3 REVIEW 4/12/15 TIPS FOR YOUR EXAM - SPEED AND ACCURACY WILL SAVE YOU - DON T GUESS UNLESS YOU HAVE TO - YOU RE SMART - YOU CAN DO THIS - DON T BE ANXIOUS OR NERVOUS - A FEW MINUTES BEFORE THE EXAM TAKE SOME TIME TO CLEAR YOUR MIND, BREATHE AND RELAX - ALL THE BEST!!!! takinyi@iastate.edu

2 Part I: Multiple Choice: (3 pts each). The answer you fill in on your bubble sheet is the one that will count. You should circle the answer on this sheet for your own reference. 1. Solutions of which ion produce a red color when vaporized in a Bunsen burner flame? a) Ca b) K c) Na d) Zn e) P 2. The spheres below represent atoms of P, Sb, N, As, and Bi (not necessarily in that order) Which one of these spheres represents an atom of Sb? a) A b) B c) C d) D e) E 3. Which is NOT a chemical reaction of the alkali metal potassium? a) K(s) + O2(g) KO2(s) b) 2 K(s) + 2 H2O(l) 2 KOH(aq) + H2(g) c) 2 K(s) + H2(g) KH2(s) d) 2 K(s) + Cl2(g) 2 KCl(s) e) 6 K(s) + N2(g) 2 K3N(s) 4. When NaF, MgO, KCl and CaS are listed in order of increasing lattice energy, which order is correct? a) MgO, NaF, KCl, CaS b) CaS, MgO, KCl, NaF c) KCl, CaS, NaF, MgO d) KCl, NaF, CaS, MgO 5. An atom of which element has the highest second ionization energy? a) Na b) Mg c) Al d)k e) Li 6. An element M reacts with nitrogen to form M3N2 and with water to form a hydroxide that is slightly soluble. The mostly likely candidate for the element M is a) Lithium b) Calcium c) Aluminum d) Silicon e) Cesium

3 7. Which one of the following chemical equations is correctly represents the formation of stable ionic compound from the reaction of Aluminum metal with Nitrogen gas? a) Al(s) + N2(g) AlN2(s) b) 2 Al(s) + N2(g) 2Al2N(s) c) 3 Al(s) + N2(g) 2Al2N3(s) d) 2 Al(s) + N2(g) 2AlN(s) e) 3 Al(s) + N2(g) Al3N2(s) 8. Which species does NOT have an octet of electrons for its outer shell? a) Mg + b) P 3 c) O 2 d) C 4 e) Al Atoms of which element, indicated by letter on the periodic table below, would be expected to have the smallest first ionization energy? A C B E D a) A b) B c) C d) D e) E 10. Which ionization process requires the most energy? a) C(g) C + (g) + e b) C + (g) C 2+ (g) + e c) C 2+ (g) C 3+ (g) + e d) C 3+ (g) C 4+ (g) + e e) C 4+ (g) C 5+ (g) + e 11. Which of the following compound has the longest C-C bond?

4 12. The electronegativity of A is 2.1 and of B is 0.3.Given that B is a metal, AB4 would be expected to be. a) be ionic and contain B- ions. b) be ionic and contain B+ ions. c) have polar covalent bonds with partial positive charge on the B atoms. d) have polar covalent bonds with partial negative charge on the B atoms. e) have polar covalent bonds with partial negative charge on the A atoms. 13. Which of the following element is expected to have large negative electron affinity? a) O b) Rb c) B d) C e) Li 14. Arrange the following in order of increasing ionic character: CsBr LaBr3 PBr3 MgBr2 a) CsBr < LaBr3 < MgBr2 < PBr3 b) CsBr < MgBr2 < PBr3 < LaBr3 c) PBr < MgBr < LaBr < CsBr3 d) PBr3 < LaBr3 < MgBr2 < CsBr e) CsBr3 < MgBr2 < LaBr3 < PBr3 Element Electronegativity Bromine 2.8 Phosphorus 2.1 Magnesium 1.2 Lanthanum 1.0 Cesium How many resonance structures does N2H2 have? a) 4 b) 2 c) 3 d) Which one of the following is expected to exhibit resonance? a) NH4 + b) HCN c) CO2 e) NO2 17. In the following electron dot structure for perchlorate ion, ClO4, the formal charges are: on Cl, and on the O atoms. a) +4, 1 b) +2, 0 c) +3, 1 d) 1, +2 e) 1, +1

5 18. Which of the following are allowed resonance forms of NCS? I N C S and N C S II N C S and N C S III N C S and S C N a) only I b) only II c) only III d) I and II e) II and III 19. Based on VSEPR theory, which should have the largest XAX bond angle? 20. The bond angles marked a, b, and c in the molecule below are approximately,, and, respectively. [You may have to complete the structure by adding necessary lone pairs of electrons] a) 109, 109, 109 b) 120, 109, 120 c) 109, 109, 90 d) 120, 180, 90 e) 120, 109, 109 bo 21. Which order is correct when the species are arranged in order of increasing bond length? a) NO 3-, NO 2-, NO + b) NO +, NO 3-, NO 2- c) NO 2-, NO 3-, NO + d) NO +, NO 2-, NO (4 pts each) For the following compounds, draw the Lewis dot structures and calculate the formal charge on each atom: PCl3, NO 2-, SiOH2, OCl -, I3-23. (3 pts) Arrange the following isoelectronic atoms in descending order: S 2-, Cl -, K +, Ca 2+ and Ar

6 Part-II: For full credit, show all your work legibly, include units, and report your answer to the correct number of significant figures. No work shown = 0 points. 24. (2 pts) When asked to give an example of resonance structures, a student drew the following. Why is this example correct or incorrect? Briefly but clearly explain. 25. (4 pts each) Complete and balance the following reaction equations. For full credit, include the phase (s, l, g, or aq) for all reactants and products. A) BaO (s) + H2O (l) B) CO2 (aq) + Na 2CO 3 (aq) + H 2O (l) C) CaCO3 (s) + H2O (l) D) Write the full reaction for the formation of Potassium peroxide E) H2O (l) + F2 (g) F) BaO (s) + H2O (l) G) NiO (s) + NiSO 4 (aq) + H 2O (l) 26. A. (6 pts) Use the given average bond enthalpies (or bond energy data) and H for the following reaction of OF2(g) with water to estimate the bond dissociation energy for O F bond in OF2 molecule. Bond Avg. Bond Energy (or bond enthalpy) kj/mol H-F C-F H-O O-O O=O F-F The O-F bond energy is kj/mol. 27. How many sigma and pi bonds are in this compound? a) 9 sigma, 6 Pi b) 10 sigma, 6 pi c) 10 sigma, 3 pi d) 15 sigma, 4 pi

7 28. (24 pts) For each chemical formula draw the Lewis structure, determine the number of regions of electron domain (density) around the central atom, draw a 3-D structure showing the geometry, indicate bond angles, write the name of the molecular geometry and indicate whether or not the molecule is polar. The NH3 molecule is shown as an example. Chemical Formula Lewis Structure (Include Lone Pairs of electrons) # of electron density around the central atom 3-D structure showing the molecular geometry (show lone pair only on the central atom, if any) Name of the molecular geometry Expected bond angle(s) at the central atom Polar or non-polar? NH3 4 Trigonal pyramidal < o Polar TeCl4 BrF5 H2CO (C is the central atom) O3 Total Page

8 Pe riodic Table of t he Element s 1 A 8 A A 3 A 4 A 5 A 6A 7 A 2 H He Li 6.94 Be B B C N O F Ne B 4 B 5B 6 B 7B 1 B 2 B Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe (9 8 ) Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn ( 2 09) (2 1 0 ) ( 222) Fr Ra Ac Rf Db Sg Bh Hs Mt Ds ( 2 23) (2 6 1 ) (2 6 2 ) ( 263 ) ( 2 62) ( 2 65) (2 6 6 ) (2 8 1 ) Lant hanides Ac t inides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu ( 1 45) Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr ( 2 37) (2 4 4 ) (2 4 3 ) ( 2 47) ( 247 ) (2 5 1 ) (2 5 2 ) ( 257 ) ( 2 58) (2 5 9 ) ( 2 60)

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