Ch. 16 & 17  equilibrium & acid / base                        test     [65 points]       Chem


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.


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1.   Determine the molar solubility of barium sulfate in water.  [10 points]



2.  Write the equilibrium constant, Kc, expression for the reaction:  ___.  [10 points]

a.  C2H6 (g)  +  O2 (g)    CO2 (g)  H2O (l)



b.  Ca3(PO4)2 (s)   



3.  Determine the value of Kc for the reaction:  N2 (g)  +  3 H2 (g)    2 NH3 (g) , where the initial concentration of nitrogen, hydrogen, and ammonia was 5.0 M, 10.0 M, and 5.0 M, respectively.  The equilibrium concentration of hydrogen is 5.0 M.  [10 points]



4.  Determine the pH of ___.  [10 points]

a.  5.0 mM HNO3, a strong aci

b.  5.0 mM KOH, a strong base

5.  For the reaction:  N2 (g)  +  3 H2 (g)    2 NH3 (g) at equilibrium, it was disturbed by  ___;  what is the effect on the moles of nitrogen and ammonia; justify your answer.  [15 points]


a.  cool the system


b.  add an inert gas, Xe, to the system at constant temperature and volume


c.  add hydrogen at constant temperature and pressure



6.  What is the pH of 5.0 mM benzoic acid, a weak acid ?  [10 points]