Chemistry 109 – Dec 2004; Exam IVversion 1

1、8CHEM 109 EXAM 4 FALL 2006 SHOW ALL WORK NO WORK NO CREDIT1. (10 pts) (a) In the box provided, diagram the complete Lewis electron dot diagram for the compound tin(II) chloride, SnCl2. (Note: Cl = chlorine!) Name the molecular shape of the compound.Number of valence electrons in SnCl2: _Molecular sh

2、ape: _(b) In the box provided, diagram the complete Lewis electron dot diagram for the anion SnCl3. (Note: Cl = chlorine!) Name the shape of the molecule. Number of valence electrons in SnCl3: _Molecular shape: _ 2. (10 pts) (a) What are the bond angles around the labeled carbon atoms? (1) NCC _ (2)

3、 CCC _ (3) CCH _(b) Look back at the structure above. How many sp hybridized carbons are present? _(c) Circle the shortest carboncarbon bond.(d) Draw an arrow to the carboncarbon bond that has the largest bond enthalpy.3. (10 pts) (a) Azodicarbonamide (shown below) is used to provide the foaming pre

4、ssure to make liquid styrene into the lightweight objects such as cups and plates. Examine the structure and answer the following questions:(i) How many carbon atoms are in this molecule? _ carbon atoms(ii) How many lone pair electrons are implied in the structural formula for azodicarbonamide? _ el

5、ectrons(iii) Circle any and all atoms that ARE NOT sp2 hybridized.azodicarbonamide(b) Methyl cyanoacrylate, the active ingredient in superglue (shown below) quickly reacts to form a type of polymer that sticks to most everything.(i) What is the hybridization of the nitrogen atom? _(ii) How many pi b

6、onds are present in the molecule? _(iii) How many atoms are sp3 hybridized in this molecule? _Methyl cyanoacrylate4. (10 pts) Because of the indiscriminate and overuse of penicillin, a number of microorganisms have been able to develop resistance to the antibiotic. A new “designer” penicillin curren

7、tly being used to combat bacterial resistance is amphotericin B; the structure is shown below.(a) Identify the functional groups that are boxed below. Fatty acids are composed of two general parts, a polar head and a non-polar tail. Oleic acid is a monounsaturated omega-9 fatty acid found in various

8、 animal and vegetable sources. It has the formula C18H34O2 .headtail(b) Is this a cis or a trans fat? Circe your choice: cis or trans(c) Is free rotation possible around the bond indicated with an arrow? YES or NO(d) What is the molecular formula of oleic acid? _(e) Circle the most polar bond in ole

9、ic acid above.(f) The saturated form of this acid is stearic acid. It is used in Lorenzos oil. How many hydrogens are required to saturate the hydrocarbon tail of this fatty acid?_5. (15 pts) (a) Diagram the Lewis dot structure of the recently discovered compound XeH2. (b) Diagram the hybridization

10、scheme for the Xe atom in the molecule XeH2. What type of hybrid orbitals are required? What is the HXeH bond angle?Draw the appropriate hybrid orbitalboxes here with the appropriate number of electrons for Xe. 5dHYBRIDIZATION5p5sFill in the ground state electron configuration of the Xe atomName the

11、 type of hybrid orbitals used for bonding in XeH2: _HXeH bond angle: _(c) Consider the molecule acetonitrile shown below. Diagram the hybridization of the indicated nitrogen atom. Include any unhybridized orbitals in your sketch.Draw the appropriate hybridized and unhybridized orbital boxes here and

12、 fill with the appropriate number of electrons. HYBRIDIZATION2p2sFill in the ground state electron configuration of nitrogenCircle the orbital in the box above that is used in sigma bond formation.(d)6. (15 pts) (a) In the boxes provided, draw one possible isomer of the molecular formula given.C4H8

13、(different than the previous isomer)C2H6O2C4H8Name each of he following compounds using systematic nomenclature rules. Write your answers on the lines provided. If a name is provided, then provide the correct structural formula in the box. (b) heptane (c) propanal(d) _(e) methyl ethanoate(f) hexanoi

14、c acid(g)_7. (10 pts) Tyrosine is an amino acid that was first discovered in 1846 in cheese. Tyrosine is used in protein synthesis and as a precursor to the skin pigment melanin.(a)How many pi-bonds are present in the molecule? (a)_(b)What is the hybridization of the carbon atom labeled #1?(b)_(c)Wh

15、at is the hybridization of the oxygen atom labeled #2? (c)_(d)How many sigma-bonds are present in the molecule? (d)_(e)What is the bond angle around the nitrogen atom? (e)_Zingerone, drawn below, is the principle organic molecule responsible for the unique taste of ginger. Fresh ginger does not actu

16、ally contain the molecule zingerone; cooking ginger transforms the molecule gingerol into zingerone.(f)How many hydrogen atoms are implied at position 1?(f)_(g)How many hydrogen atoms are implied at position 2? (g)_(h)Draw and arrow to any ketone group.(i)Circle the most polar bond.(j)Is free rotati

17、on possible around the bond at position 3?(j)_8. (15 pts) (a) Draw the product of the following reaction in the box provided:ethyl cinnamate (cinnamon fragrance)(b) The compound N,N-diethyl-m-toluamide (or DEET) is used in insect repellants. In the boxes below, draw two organic molecules that could

18、react in a condensation reaction to form DEET.+(c) What by-product is formed in the condensation reactions above?(d) Name the following branched hydrocarbon: _9. MULTIPLE CHOICE (2 pts each). Circle the ONE best choice to answer each of the following questions1. Which of the following is the most polar?(e)(d)(c)(b)(a)2. Which of the following makes an accurate claim about double bonds?(a) double bonds typically have lower bond enthalpy values than single bonds(b) double bonds limit th