Unit B Report I Answers

Unit B Report I Answers - Sec. 001 Report I, Unit B BMB 471...

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Sec. 001 Report I, Unit B BMB 471 – Report I – Experimental Unit B Answers 1. ----------------------------------------------------------------------------------------- a. Submit a plot of the data collected in B.5.a.(1) and indicate the estimated pK a ’ on the plot. i. Attached separately as Figure 2-1. b. What was the pH of your 30 mM phosphate buffer when the pH meter was used? i. 7.59 c. If you had prepared your 30 mM phosphate buffer by using the quantities of conjugate acid and the base calculated from the H-H equation, would the pH be the same or different as in question 1b? Explain your answer. (If your answer is different, state in which pH direction it would be different and why). i. Using the concentrations of conjugate acid and base calculated from the Henderson-Hasselbach equation (0.02 M base / 0.01 M acid) would have resulted in a pH (7.50) different from the pH of question 1b (7.59). This is only due to a procedural error, where an extra 0.25 mL of base was added after the solution was brought to a pH of 7.5. Otherwise, the calculated pH and experimental pH were of the same value. 2. ----------------------------------------------------------------------------------------- a. What was the pH of the following? i. 30 mM phosphate buffer: 7.59 ii. Primary standard pH 6.87 buffer: 6.73 iii. Tap water: 7.17 iv. Tap-deionized water: 5.13 v. Glass-distilled water: 4.58 b. What is the calculated pH of the standard pH 6.87 buffer? i. 7.218 3. ----------------------------------------------------------------------------------------- a. Explain how you prepared 10 mM (changed from 20 mM to 10 mM as per Dr. Bowlby) potassium phosphate (pH 7.5) containing 1 M (NH 4 ) 2 SO 4.
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This note was uploaded on 03/19/2008 for the course BMB 471 taught by Professor Bowlby during the Spring '08 term at Michigan State University.

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Unit B Report I Answers - Sec. 001 Report I, Unit B BMB 471...

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