Ch. 16  equilibrium II              test     [80 points]                               AP 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.

                                                                                                Signature:  ___________________

1. What is the pH of 125 mL of 10.0 mM lactic acid ?   [15 points]

2. What is the pH of 125 mL of 10.0 mM sodium lactate ?  [20 points]

3. A solution is prepared from 0.0250 mole of HCl, 0.10 mole propionic acid, C2H5COOH, and enough water to make 0.365 L of solution.  Determine the concentrations of  H3O +, C2H5COOH, C2H5COO -, and OH - in this solution.  Ka for propionic acid = 1.3 * 10 -5.  [15 points; hint:  HW problem 1974]

4. Describe and rationalize the trends in acid strength containing atoms in a ___ of the periodic table; clearly state the direction of “moving” in the periodic table, e.g. top to bottom or bottom to top.   [10 points]

a.  row

b. column

5. Old topic:  Describe how to prepare 1.0 L Krebs-Ringer’s solution, which contains  __ using the below stock solutions / powder. [20 points]

                 Contains                                                                               use stock solution / powder
115 mM NaCl                                                                                      500. mM
5.9 mM KCl                                                                                          100. mM
1.2 mM MgCl2                                                                                     100. mM
1.2 mM NaH2PO4                                                                                100. mM
1.2 mM Na2SO4                                                                                   100. mM
2.5 mM CaCl2                                                                                      100. mM
25 mM NaHCO3                                                                                   powder
10 mM glucose (C6H12O6)                                                                  powder
pH 7.4                                                                                    bubble with 5% CO2 / 95% O2
source:  http://www.chemicalforums.com/index.php?topic=21167.0