Ch. 16 & 17 equilibrium & acid / base /   test  [70 points]                    Honors Chemistry

Show your work in an organized manner, includes any relevant equation / formula, proper units in your work / answer, and the proper number of significant figures in your answer.

Academic Honesty:   The answers on this test are my own.  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 do not sign or violate any of the preceding items, your semester grade is a F.

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1.  What is the pH of  ___.  [10 points]

a.  5.0 mM HCl (strong acid)

b.  5.0 mM KOH (strong base)


2.  A buffer contains benzoic acid and sodium benzoate (C6 H5 COONa).  Write the net ionic equation involving the reaction between the buffer and ___.  [10 points]

a.  HNO3   (strong acid)

b.  NaOH  (strong base)

3.  Calculate the pH of 75 mL of 1.0 mM benzoic acid (C6 H5 COOH;  Ka = 6.5 * 10-5 )   [10 points]


4.  What is the solubility of barium fluoride in water ?  [8 points]


5.   The combustion of ethane:  C2 H6 (g)  +  02 (g)  <-->  CO2 (g)   +  H2 O (g)   generates heat.  Upon reaching equilibrium, the system was disturbed by  ___; what is the effect on the [O2 ] ?  [CO2 ] ?  Rationalize your answer.  [12 points]

a.  decrease in volume
b.  addition of water vapor
c.  addition of Ne
d.  cooling the system


6.  N2 (g)   +  H2 (g) <--> NH3 (g)

5.0 moles of N2 and 10.0 moles of H2 were added to a 20.0 L containter at 500 K.  At equilibrium, there was 3.0 moles of N2 ; what is Kc of this reaction ?  [10 points]


7.  H2 (g)   +  I2 (g) <--> 2HI (g)   Kc = 10

The initial concentration of H2 and I2 are 5.0 and 7.0 mM, respectively.  What is the equilibrium concentration of HI ?  [10 points]