Practice Exam 3_McCord-1

# Practice Exam 3_McCord-1 - Practice Exam 2/3 1 When a...

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Practice Exam 2/3 1. When a moderate amount of acid is added to a buffer, the pH should: 1. Decrease greatly 2. Increase greatly 3. Decrease slightly 4. Increase slightly 5. Stay the same 2. A buffer solution is made by dissolving 0.51 moles of a primary amine (R-NH 2 ) and 0.21 moles of HCl into 624 mL of solution. What is the pH of this buffer? K b is 3E-6 for R-NH 2 . Your answer must be within +/- 0.35% 3. A buffer solution contains 0.0200 M acetic acid and 0.0200 M sodium acetate. What is the pH after 2.0 millimoles of HCl are added to 1.00 L of this buffer? pK a = 4.75 for acetic acid. 1. 4.84 2. 4.66 3. 4.80 4. 4.75 5. 4.70 4. The solubility product constant of PbCl 2 is 1.7E-5. What is the maximum concentration of Pb 2+ that can be in ocean water that contains 0.0500 M NaCl? 1. 3.4E-3 M 2. 6.8E-3 M 3. 4.2E-8 M 4. 1.7E-3 M 5. 8.5E-7 M 5. Calculate the ratio of the molarities of HPO 4 2- and H 2 PO 4 - ions required to achieve buffering at pH=7.00. For H 3 PO 4 , pK a1 =2.12, pK a2

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## This note was uploaded on 04/18/2011 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

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Practice Exam 3_McCord-1 - Practice Exam 2/3 1 When a...

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