CHE 241 Organic Chemistry Instructor: Dr. Dexter L. Criss Exam #1 Student?s Full Name (Print) Student?s Full Name (Write) NOTE: Sharing of calculators is strictly prohibited. Violators will receive a ?0? grade for the exam! Use of WiFi devices is strictly prohibited during testing. ALL personal items must be stored outside the testing area. Remember, no hats or caps are allowed during the exam! NO PENS. Pencils only. Good Luck!!! I. Calculate the formal charge of the indicated atoms. 4 pts II. Consider the molecules below and determine if the two formulas represent the same compound, isomers or different compounds (which are not isomers). 6 pts and and and C C H H N O H H H III. Please explain (USING FIGURES) why dimethyl ether is more soluble in water than dimethyl sulfide. 6 pts CH3OCH3CH3SCH3 C1 C2 O1 N1 C1 ________ C2 ________ N1 ________ O1 ________ Atom Charge IV. Identify each functional group below. Omit alkane and cycloalkane. 8 pts V. Please predict the isomer with the highest melting point? Please explain. Also, which molecule is most stable? Explain your answer. 8 pts VI. Arrange the following compounds in order of decreasing acidity. Explain briefly this trend. (1 most acidic) 3 pts OH N CH3 CN CH3O O CH2 C C H Cl A) B) OH O Br OH O H OH O F Highest Melting Point isomer is: ____________ Explanation: Most Stable isomer is: ____________ Explanation: VIII. Please elucidate compound Q with a molecular formula of C4H6. The IR spectrum shows peaks at 2950 (medium) and 2200 cm-1 (weak). 8 pts. VII. Derive fully the pKa expression for the reaction below. 10 pts HA H2O A - H3O + + + IX. From the list below give the nomenclature of each structure. 12 points X. Draw 3-D structures for the compounds below. Also indicate the hybridization of each carbon atom. 5 pts CH4 C2H4 CH3 H CH3 H C CH3 H3C H3C C2H2 XI. Draw the Newman Projection conformers for butane. Rotate from 0 to 360 degrees along the C2-C3 bond. Label each conformer; indicate stability. Plot a potential energy diagram show the relative stabilities of this conformers. 12 pts XII. Predict the direction of the reaction below. Hint (pKa). 5 pts OH ++ O NaOHHOH Na CH3 CH3 H H CH3 CH3 H H I II XIII. Which isomer would you expect to have the larger heat of combustion (least stable)? Briefly explain your choice. 10 pts. H CH3 CH3 H I CH3 H CH3 H XIV. Briefly explain why cyclobutane?s ring strain energy is very large. 8 pts. IR T a b le T ab le o f A p p ro x im at e p K a o f C o m m o n C o m p o u n d s
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