Ch. 15 & 16  equilibrium& acid / base  test      [100 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. 


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.  Write the algebraic expression for the following chemical reaction s.  [10 points]


a.  mixing aqueous solutions of calcium nitrate and potassium phosphate.



b.   the combustion of propane (assume all chemicals in the reaction are gases)

2.   For the reaction:  N2(g)  +  3 H2(g)      2 NH3 (g)  at 27 °C, its Kc = 25.  What is the numerical value of __ ?  [10 points]

a.  Kp of  :  N2(g)  +  3 H2(g)      2 NH3 (g)  at 27 °C.


b.   NH3 (g)    ⇄   N2(g)  +   H2(g)  



3.  What is the numerical value of the Kp for N2(g)  +  3 H2(g)      2 NH3 (g)  if the initial partial pressures of nitrogen, hydrogen, and ammonia is 225 torr, 375 torr, and 835 torr, respectively, and the equilibrium partial pressure of  hydrogen is 125 torr.  [10 points]



4.  What is the effect on the amount of NH3 in the reaction:  N2(g)  +  3 H2(g)      2 NH3 (g)  at equilibrium due to __; justify your response.  [15 points]


a.  cooling the system ?


b.  addition of He; the pressure remains constant


c.  addition of He; the volume remains a constant



5.  What is the pH of __ .  [20 points]


a.  15.0 mM pyridine



b.  15.0 mM methylamine chloride


6.  The pH of a solution of 175.0 mM acetic acid and 0.10 mM hydrochloric acid is __.  [10 points]




7.  Write the chemical equation describing the reaction between water and  __; identify and label (e.g weak base vs. conjugate base) ALL conjugate pairs.  [10 points]


a.  lactic acid:


b.  aniline:



8.  write the net ionic equation for __.  [15 points]


a.  adding solid lithium hydroxide to a solution of hydrogen fluoride



b.  mixing aqueous solution of sodium bicarbonate and potassium hydroxide



c.  mixing solutions of acetic acid and sodium hydroxide



d.  add copper into a concentrated solution of ammonia



e.  add magnesium into an acidic solution of potassium permanganate