CEMISTRY 140A NAME (please print) MIDTERM EXAM IRST LAST JULY 13, 2011 SIGNATURE Vollhardt & Schore 6 th Edition Cp. 1 through 5 ID NUMBER LAST NAME PERSN SEATED IN T YUR RIGT: LAST NAME PERSN SEATED T YUR LET: D NT PEN TE EXAM UNTIL YU ARE TLD T D S Please sign your name on the top of each page. No points will be given for pages not signed. Check to see that you have 6 pages (including this one). Answer in the space provided. Do not write answers on the back of a page. The one blank page may be used for scratch work, but D NT use the scratch page for answers. Question Points Score 1. 45 2. 60 3. 55 4. 40 Total 200 e Li Be B C N Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn e 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 Cs Ba La f Ta W Re s Ir Pt Au g Tl Pb Bi Po At Rn
NAME: 2 1a. n the reaction coordinate diagram shown below, draw the potential energy level diagram for the reaction of water with acetic acid (C 3 C 2 ). Label the energy level for the starting species and products and show each as a Lewis structure (not in 3-D). Indicate the position of all intermediates with an I and all transition states with TS. You need not show transition state structures. Label the activation energy as E a on your diagram. Indicate the position of the equilibrium qualitatively by clearly indicating the relative energies of the starting species and the products. E Reaction Coordinate 1b. or each of the following one-step transformations show the movement of electrons by using the standard curved-arrow notation. Show all formal charges for each structure on the left and right of the reaction arrows. a) b) C C C Al 2 C N N C C C 3 C N N Al c) I C Br C I Br
NAME: 3 2a. Draw the three most significant resonance contributors for each of the following species. Indicate which is the least important contributor of the three by circling it. Indicate which is the most important contributor(s) of the three by drawing a box around it. Notice that below each molecular formula, you have been give the order in which the atoms are connected. All of your drawings should be Lewis structures. You may use lines to indicate pairs of bonding electrons. a) C 3 C 2 3 C C b) C 2 5 2 3 C C 2b. or each of the following molecules indicate the shape (geometry) of the molecule as one of the following: tetrahedral, trigonal planar, trigonal pyramidal, bent, or linear. In each case label the hybridization state of the central atom. a) [N] - b) [CN] - c) C 3 + d) B 4 -
NAME: 4 3a. or each structure shown below, show the Newman projection which corresponds to the view down the bold bond from the indicated direction. In the Newman projection you need only show the atoms attached directly to the carbons connected by the bold bond. If there is a more stable conformation for the molecules shown on the left, draw it in the box to the right (do not give a Newman projection). If there is none then write "none". Newman Projection More stable conformer? Br Newman Projection More stable conformer? 3b. or the two structures that you were given in part 3a, label every stereocenter as either the R or S configuration. If you gave a more stable conformer in the boxes to the right in part 3a, then label the configurations for each stereocenter in your structure. 3c. or the cyclohexane derivative that you were given in part 3a, show all the possible stereoisomers using flat cyclohexane rings that are drawn in the plane of the page.
NAME: 5 4a. or the structure given below circle all tertiary carbons and star all primary carbons. C 3 C 3 C 3 4b. or the structure given below circle all of the functional groups and give the name for each group. ow many stereocenters are there in this molecule? S N 2 4c. ow many stereoisomers are there for each of the following compounds (you need not draw them): i) C 3 CBrC 2 CBrC 3 ii) C 3 CBrCBrC 2 C 3 iii) C 3 CBrCBrCC 3 iv) C 3 CBrCBrC 2 C 2 4d. Give the structures for two diastereomers of C 3 CBrCBrCC 3 :
NAME: 6