CHEM 3530 - Exam 4 – April 23, 2010(75) PART I. MULTIPLE CHOICE (Circle the ONE correct answer) 1. What is the approximate pH of a solution prepared by mixing 100 mL of 0.5 M NaOH with 200 mL of 0.3 M HCl? (A) 0.4 (B) 1.5 (C) 2.0 (D) 12.5 2. For the base, aniline (C6H5NH2), pKb- 9.37. What is the approximate pH of a 0.005 M solution of anilinium chloride (C5H5NH3Cl)? For #3 - #6: Consider hypobromous acid (HBrO), which has an acid dissociation constant, Ka= 2.0x10-9. 3. What is the pH of a 0.20 M solution of aqueous hypobromous acid? 4. What is the pH of a 0.20 M solution of aqueous potassium bromite (HBrO)? 5. What is the pH of a solution after 0.20 moles of HCl are added to a 2 L solution of a 0.40 M solution of potassium bromite? (A) 8.2 (B) 4.8 (C) 9.2 (D) 5.8 6. What is the value of the ratio, [HBrO]/[BrO-] at pH = 9.1: 7. In class, we discussed the buffering action of the CO2/HCO3-and Hemoglobin (Hb) buffers in controlling the pH in blood? Which of the following statements is/are true? (i) Because the principal metabolism products are carboxylic acids, the large excess of CO2relative to HCO3-, makes this a suitable buffer to remove the added acid. (ii) CO2produced in the muscles raises the pH of the blood, which is then lowered by the Hb buffer. (iii) The Hb molecules in blood transport the CO2produced by exercise from the muscles to the lungs.
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