Organic Chemistry Test Questions

1_____2_____3_____4_____5_____6_____7_____8_____9_____TOTAL________ CHEM 237, FALL 2007 HOUR EXAM 1 Name________________________________________________________ TA Name _______________________ __& Section # _________________ Student #______________________________________________________

1. (9 pts) Write a valid Lewis structure for each of the following. Show lone pairs and formal charges where necessary. Draw covalent bonds as lines. (a) bisulfate ion, HSO4-

O HO S O
(b) hydrogen cyanide, HCN

O

H C

N

(c) hydrazoic acid, HN3 (arranged HNNN)

H N

N

N

or

H N

N

N

2. (10 pts) Indicate which of the following pairs do not constitute resonance structures by drawing an “X” in the space provided?

O CH3C-O O

-

O and

-

CH3C O OH

CH3C-OH O CH3CCH3

and

CH3C O OH CH3C CH2

X X X X

and and and

-

CH2CH CH 2 HOCN

+

CH2 CH CH2

HNCO

3. (8 pts) What is the hybridization of the Carbon indicated in bold in the following compounds?
H2C=O

sp2

C

sp2

H

C C

Br

sp

CBr4

sp3

4. (10 pts) Malonic acid, HO2CCH2CO2H, is a diprotic acid. The pKa for the loss of the first proton is 2.83; the pKa for the loss of the second proton is 5.69. (a) Explain why malonic acid is a stronger acid than acetic acid (pKa = 4.75). (b) Explain why the anion, -O2CCH2CO2H, is so much less acidic than malonic acid itself. (a) electron withdrawing –CO2H group stabilizes charge of conjugate anion (b) molecules doesn’t want to be dianion

5. (11 pts) Carey. All the parts of this problem refer to the alkane having the carbon skeleton shown.

(a) (2 pts) What is the molecular formula of this alkane? C13H38

(b) (2 pts) What is the IUPAC name? 5-ethyl-2,6-dimethylnonane 1 pt for or 1 pt for 5-ethyl-4,8-dimethylnonane 2,6-dimethyl,5-ethylnonane

(1 pt) How many methyl groups are present in this alkane?____5 (1 pt) How many methylene groups?______5______ (1 pt) How many methine groups?_________3___