Name:  ______________________________                                   period:  _______

Solution & thermodynamics  test         [100 points]                         Honors 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. 

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.

                                                                                                Signature:  ___________________

 

1.  70% HNO3 has a density of 1.42 g / mL.  What is the  ___ of HNO3 in this solution ?  [30 points]

a.  molality

b.  molarity

c.  mole fraction

 

2.  How to prepare 275 mL of 25 mM glucose (C6 H12 O6 ) aqueous solution using  __.  [20 points]

a.   75 mM glucose and water

b.  solid glucose and water

 

3.  What is the concentration of the lead cation in 25 mL aqueous solution of lead (II) nitrate before the addition of excess sodium chloride if 1.0 g of a precipitate was formed ?   [15 points]

 

4.  How much heat would be produced by the combustion of 5.0 g of C2 H6 (assume form liquid water)  ?  [15 points]

 

5.  Given:

                    SO2  -->  S  +  O2                                    Δ H = 296.8 kJ
      2 SO2  +  O2  -->  2 SO3                                         Δ H = - 198 kJ

find:            S  +  (3 /2)  O2  -->  SO3                                           Δ H  =  ?                                 [15 points]

 

6.  Is the change in entropy to dissolve calcium chloride in water:  positive ?  negative ?  ambiguous ?  justify your response.  [5 points]

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Solution & thermodynamics  retest       [100 points]                         Honors 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. 

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.

                                                                                                Signature:  ___________________

1.  15.84 M HNO3 has a density of 1.42 g / mL.  What is the __ of HNO3 in this solution ?  [15 points]

a.  molality

b.  (mass) %

c.  mole fraction

 

2.  15 mL of 55 mM phosphoric acid (hydrogen phosphate) titrates 65 mL of calcium hydroxide.  What is the concentration of calcium hydroxide ?  [10 points]

 

3.  How to prepare 875 mL of 25 mM sodium carbonate ?  [10 points]

 

4.  5.0 g solid sodium nitrate was added to 45 mL of water at 21 °C; what is the temperature after all of the sodium nitrate was dissolved in the water ?  [20 points]


5.  Implication / rationalize the difference in ΔS of   [10 points]

NaCl(s)  -->  NaCl (aq)            ΔS  >  0
NaOH(s)  -->  NaOH (aq)         ΔS  <  0 

 

6.  For ethanol, C2 H5 OH, the freezing and boiling point is – 114 °C and 78 °C, respectively.  The specific heat of ethanol in the solid, liquid, and gas is 0.85 J / (g K), 1.12 J / (g K), and 0.78 J / (g K), respectively.   The heat of fusion and heat of vaporization is 4.9 kJ / mol and 39 kJ / mol, respectively.

How much heat would be needed to heat 10.0 g ethanol at – 114 °C as a liquid to a gas at 78 °C ?  [15 points]


7.  Experimental design:  briefly describe an experimental method to  __  and include ALL experimental measurements  (not subsequent calculations).   [20 points]

a.  determine ΔH to dissolve 1.0 gram of solid lithium chloride in 35 mL of water.

b.  determine the [Pb2+ ] in a 75 mL aqueous solution of Pb(NO3 )2