Ch. 4, 13, 24.1, & 16.11 solution & chemical reactions test   [80 points]       AP Chemistry

 

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.

 

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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. 

 

 

1.  Describe how to prepare the following solutions; show relevant calculations.  [10 points]

 

a.  325 mL 25 mM calcium chloride

 

b.  325 mL 25 mM calcium chloride using a 135 mM calcium chloride solution.

 

 

2.  A 70.0% nitric acid (HNO3) has a concentration of 15.9 M.  [15 points]

 

a.  what is the solution’s molality ?

 

b. what is the solution’s density ?

 

 

 

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.  Give the formulas to show the reactants and products for the following chemical reactions.  Each occurs in aqueous solution unless otherwise indicated.  Represent substances in solution as ions if the substance is extensively ionized.  Omit formulas for any ions or molecules that are unchanged by the reaction.  In all cases a reaction occurs.  You need not balance (the coefficients in the reactions)  [15 points]

 

a.   potassium metal added to water

 

b.  tetraphosphorus deca-oxide in water

 

c.  mix solutions of barium nitrate and sodium sulfate

                    

d.  mix solutions of sodium bicarbonate and acetic acid (or hydrogen acetate)

 

e.  add concentrated ammonia to a solution of zinc chloride

 

 

5.   Experimental design:  determination of the molar mass of a compound.   [10 points]

 

a.  list the experimental measurements (not calculations) to determine the molar mass of a nonvolatile nonelectrolyte using freezing point depression.

 

b.  describe the data analysis (i.e. show equations) using the above information.

 


6.  The boiling point of chloroform, CHCl3, is 61.2 °C, its Kb = 3.63 °C /m and Kf = 4.68 °C / m.  A fatty acid contains 72.0% carbon, 12.0% hydrogen, and 16.0% oxygen.  A solution containing 1.5 grams of the fatty acid dissolved in 10.0 grams of chloroform has a boiling point of 63.92 °C.   [20 points]

 

a.  what is the molality of the fatty acid in solution ?

 

b.  what is the molar mass of the fatty acid ?

 

c.  what is the chemical formula of the fatty acid ?