Ch. 11 & 3 intermolecular force & stoichiometry [80 points] AP Chemistry

For problems involving calculation, show your work in an organized manner, which includes any relevant equation / formula, proper units in your work / answer, and the proper number of significant figures in your answer.

1. Using concepts involving intermolecular forces, describe the basis of adsorption chromatography. [10 points]

2. old topic: Refer to the Bohr model of an atom and an equation (define all terms in the equation) to describe “effective nuclear charge”. [10 points].

3. Vapor pressure versus temperature curve [15 points]

a. sketch a vapor pressure versus temperature curve for methanol (or methyl alcohol), methane, and ethane. Label each curve with the appropriate chemical.

b. justify / rationalize your answer.

4. Balance the following chemical reactions using the lowest ratio of integers and put a “1” as appropriate; an empty blank will be considered as an error. [15 points]

a. ____ Cu + ____ HNO₃ --> ____ Cu(NO₃)₂ + ____ NO₂ + ____ H₂O

b. ____ S₄ + ____ BCl₃ + ____ H₂ --> ____ HCl + ____ BS

c. ____ CH₃(CH₂)₂CH₃ + ____ O₂ --> ____ CO₂ + ____ H₂O

5. Determine the % yield in the following chemical reaction: [15 points]

2.5 g CH₃CH₃ + excess O₂ --> CO₂ + 2.5 g H₂O

6. A compound contains:

32.73 % carbon

63.64 % chlorine

3.64 % hydrogen

determine the empirical formula of the compound. [15 points]