Ch. 4, 13, 24  chemical reactions & solution             test      [85 points]                   AP Chemistry

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 the preparation of the following solutions. [20 points]


a. 250. mL of 25 mM magnesium nitrate

b. 250. mL of 25 mM magnesium hydroxide using a 150. mM solution of magnesium hydroxide

2.  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. [15 points]

a. mix solutions of calcium fluoride and lithium phosphate

ii. how many moles of the precipitate would be formed by mixing 5 moles of calcium fluoride and 5 moles of lithium phosphate ?

b. potassium metal is added to water

ii. identify the oxidizing agent

c. add zinc metal to a solution of concentrated sodium cyanide

ii. identify the Lewis acid in the above reaction

3. A solution of 80.5 g of vitamin C (C6 H8 O6 ) in 210. g of water has a density of 1.22 g / mL. Calculate ___ of vitamin C in the solution. [ch. 13.21 problem; 20 points]


a. mass percent

b. mole fraction

c. molality

d. molarity

4.   Describe an experimental method and its anticipated results to differentiate a solution of copper (II) sulfate from other potential solutions: [10 points]
BaCl          CuCl2                 Na2 CO3  
Ba(OH)2        Cu(NO3 )2          NaI
                      CuSO4              NaOH
                                               Na2 SO4

 

5. 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 empirical formula of the fatty acid ?

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

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Ch. 4, 13, 24  chemical reactions & solution             retest   [85 points]                   AP Chemistry

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 an experimental method and its anticipated results to differentiate a solution of potassium carbonate from other potential solutions: [10 points]
AgNO3            CuCl2               K2 CO3  
Ag2 SO4         Cu(NO3 )2          KI
                      CuSO4              KOH
                                               K2 SO4


 

2.  How to prepare 250. mL of 35 mM iron (III) nitrate using a 175 mM solution of iron (III) nitrate ?  [10 points]

 

3.  In regards to the complex ion involving tin (II) and hydroxide   [10 points]

a.  what is the name of the type of bond between the metal and ligand ?

b.  describe the formation of this bond [hint:  draw the Lewis structure of the ligand]

c.  what is the coordination number in this complex ion ?

d.  what is the chemical formula of this complex ion ?

 

4.  For each of the following reactions, in part (i) write the BALANCED equation and in part (ii) answer the question about the reaction without a calculator. 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. [15 points]


a.  the combustion of methane in air

ii.  what are the oxidation numbers of the species (before & after oxidation) that was oxidized ?

b.  mix solutions of iron (III) nitrate and sodium sulfide

ii.  how many moles of the precipitate would form by mixing 5 moles of each reactant ?

c.  solid copper was added to a solution of potassium permanganate in an acidic solution

ii.  identify the type of reaction

5.  Excess sodium carbonate was added to a 25 mL solution of zinc nitrate forming 1.0 g of a precipitate.  What was the concentration of the zinc ion before the addition of sodium carbonate ?  [10 points]

6.  A solution of 17 g of HCl in 75 g of water has a density of 1.05 g / mL. Calculate ___ of HCl in the solution. [20 points]
a. mass percent

b. mole fraction

c. molality

d. molarity

 

7.  15 mL of 75 mM calcium hydroxide was needed to reach the equivalence point in the titration of 85 mL of phosphoric acid.  What is the concentration of phosphoric acid (before the titration) ?  [10 points]