Ch. 8 & 9  chemical bonds & VSEPR            test     [90 points]                   AP Chem

 

For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.              

 

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

 

                                                                                                Signature:  ___________________

 

1.  Is  __ a polar or nonpolar compound ?  Justify your response.  [10 points]

 

a.  ether with methyl groups

 

b.  alcohol with an ethyl group

 

 

2.  sketch all Lewis structures of the nitrate ion  [4 points]

 

3.  Fill-in the below table  [26 points]

 

# bonding pair electrons

# nonbonding pair electrons

Bond angle(s)

Name of molecule’s shape

Sketch molecule

 

 

3

 

 

 

2

 

 

 

 

 

 

 

 

0

 

120°

 

 

 

 

 

 

 

 

109°

 

bend

 

 

 

 

 

 

 

 

Square planar

 

 

3.  In regards to acetic acid, CH3COOH, a carboxylic acid,  [20 points]

i.  identify the hybrid orbital(s) needed in each carbon (clearly identify the appropriate carbon atom).  Justify your response. 

 

ii.  use valence bond theory to describe the bonds involving each carbon (clearly identify the appropriate carbon atom); need not show formation of the hybrid orbital.

 

 

4.  What is the relative bond angles between  __; rationalize your response.  [15 points]

 

ammonia (NH3)

chloroform (CHCl3)

chlorite ion (ClO2 - )

 

 

5.  old topic:  lab involving an aqueous solution of potassium permanganate, which is purple.  [15 points] 

 

a.  what is a calibration curve ?  what is the purpose of a calibration curve ?

 

 

b.  What is the best color of light to be used for a calibration curve:  purple or green; justify your answer.

 

 

c.  what is the potential effect of your fingerprints on the cuvette in the determination of the  ?  include the basis of your answer ?