Name:  ______________________________                                                date:  _______

 

Ch. 3 & 11 IMF & stoichiometry          test     [100 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.                  Write your answers on separate sheets of paper; clearly identify the question done; attach this sheet to the front of your exam.

 

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.   The combustion of 1.00 g of a carboxylic acid in the presence of excess oxygen generates 1.784 g of carbon dioxide and 0.730 g of water.   What is the empirical formula of the compound ?   [25 points]

 

2.  What is the % yield in this reaction:  10.0 g Ca(NO3)2  +  5.00 g Na3PO4  à  4.0 g Ca3(PO4)2  +  NaNO3  [20 points]

 

3.  Rationalize the following relative boiling points using concepts involving IMF.  [20 points]

Chemical structure

Dipole moment (D)

Boiling point (°C)

 

  (ether)

 

1.24

 

11.0

 

  (aldehyde)

 

 

2.83

 

49.0

butane

 

?

- 1.0

 

4.  In regards to London IMF, describe its basis / presence in __.   [20 points]

a.  nonpolar compound; define / refer to the terms, temporary dipole & induced dipole in your response.

b.  polar compound;  define / refer to the molecule’s dipole moment in your response.

5.  Based on the following chemical structures,   [15 points]

and concept involving IMF, rationalize the following experimental observations

a.  both dyes remain in the cartridge when eluated with water

b.  both dyes came out of the cartridge together when eluated with 70% alcohol

c.   identify / justify the 1st dye to be eluated using 15% alcohol