Exam 3 - CHM 3120 Exam 3 (Form Code A) April 2nd, 2009...

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CHM 3120 Exam 3 (Form Code A) April 2nd, 2009 Instructions: On your scantron sheet enter your name, UF ID number (start on the first space and leave the last space blank), and Form Code (see above). This exam consists of 20 (+2 bonus ) multiple choice questions each worth 10 points for a total maximum of 200 pts. You may retain your exam sheet. Turn in only the scantron. Bubbling errors of any kind will count as an incorrect response or result in the loss of points. 1. In the titration of 100.0 mL of 0.100 M KOH with 1.00 M HCl. Find the pH of the solution when 12.0 mL of the acid was added. (1) 1.75 (2) 1.99 (3) 8.12 (4) 9.75 (5) 12.25. 2. A solution of acetate acid (pK a = 4.756) was titrated with 1.00 M NaOH. The acetate acid solution had a volume of 100.0 mL and a concentration of 0.100 M. How much NaOH solution was needed to make the pH of the solution equal to 5.76. (1) 50.0 mL (2) 8.79 mL (3) 9.09 mL (4) 18.1 mL (5) 30.2 mL 3. In a typical Kjeldahl nitrogen determination assay, the final product is a mixture solution of NH 4 + ions in HCl solution. When the equivalent point is achieved for the titration of HCl, the concentration of NH 4 + is 0.01 M. Please calculate the pH of the solution (pK b of NH 3 is 4.755). (1) 5.62 (2) 6.54 (3) 7.00 (4) 7.12 (5) 5.26 4. Which of the following statements is incorrect (Temperature is assumed to be 25 o C). (1) An acid-base indictor is itself an acid or base whose various protonated species have different colors. (2) At the equivalence point of a titration of a weak base with strong acid, the pH of the solution is smaller than 7.00. (3) At the end point of a titration of weak acid with a strong base using Thymol blue (pK 1 =1.7, pK 2 =8.9) as an indicator, the pH of the solution is always larger than 7.00. (4) In an acid-base titration experiment, a Gran plot is used to find the end point of this titration. The beauty of Gran plot is that it uses the data at the end point to find the end point.
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This note was uploaded on 09/10/2009 for the course CHM 3120 taught by Professor Harrison during the Spring '08 term at University of Florida.

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Exam 3 - CHM 3120 Exam 3 (Form Code A) April 2nd, 2009...

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