Ch. 4, 13, 24  solution, colligative properties, & reactions  test         AP Chem


1.  An aqueous solution of 68% nitric acid, HNO3 , has a density of 1522 kg / m3 .  [10 points] 

a. What is the molality of the solution ?

b.  What is the molarity of the solution ?

2.  Example of AP Q4 question.  For each of the following reactions, in part (i) write the BALANCED equation and in part (ii) answer the question about the reaction.  Coefficients should be in terms of lowest whole numbers.  Assume that solutions are aqueous unless otherwise indicated.  Represent substances in solutions as ions if the substances are extensively ionized.   [20 points]

a.  Mix solutions of lead (II) nitrate and potassium chloride.


ii.  what type of reaction is shown above ?

b.  Iron (III) hydroxide was added to a concentrated solution of sodium hydroxide.


ii.  the Lewis acid in the above reaction is  _______________.

c.  The combustion of butane.


ii.  identify the oxidizing agent.

d.  Solid sodium carbonate was added to a solution of acetic acid (i.e. hydrogen acetate)


ii.  3.0 moles of sodium carbonate reacts with  __ moles of acetic acid; may not use a calculator.


3.  Excess sodium carbonate was added to a 75 mL solution of zinc nitrate, which formed 1.0 g of a precipitate.  What was the concentration of zinc in the solution prior to forming a precipitate ?  [10 points]


4.  What is the basis of the “bends” (or decompression sickness) ?  [hint:  Henry’s law; 5 points]

5.  1.0 g of a nonelectrolyte solute was dissolved in 20.0 g of benzene, C6 H6 .   The freezing point of the solution is 1.23 °C.  The freezing point of benzene is 5.5 °C; Kf = 5.12 °C / molal.  [25 points]

a.  How much did the solute reduce benzene’s freezing point ?  That is, what is the freezing point depression ?

b. What is the molality of the solute in the solution ?

c.  How many moles of solute are in the solution ?

d.  what is the molar mass of the solute ?

e.  the solute’s empirical formula is CH2 O; what is the chemical formula of the solute ?