Ch. 3 & 11 stochiometry & IMF          test                70 points                                  AP chemistry

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

1. What is the empirical of a carboxylic acid based on the following results  [15 points; weekly quiz question]

2.0 g carboxylic acid  +  excess O2  → 3.5676 g CO2  +  1.4595 g H2O

2. Fill-in the blank:  5.0 g C2H6  +  15.0 g O2 →   __ g H2O  +  CO2  [10 points; weekly quiz question]

3. The dipole moment of NH3 is greater than NF3.  Rationalize / justify.  [10 points; Re. email]

4. Describe London IMF in the context a nonpolar compound; include the terms, temporary (or instantaneous) dipole and induced dipole, in your response and the basis of the preceding dipoles.  [10 points; weekly quiz question]

5. Sketch the vapor pressure versus temperature graph showing the relative plots for carbon tetrafluoride and carbon tetrachloride.  Justify / rationalize your answer.  [10 points; weekly quiz question]

6. Old topic:  lattice energy.  [15 points; past retest question]

a.  What is lattice energy ?

b. Which chemical, sodium fluoride or potassium fluoride, has a larger lattice energy ?  rationalize your answer.