BufferNoncovalentEQ-1

BufferNoncovalentEQ-1 - Buffer and Noncovalent Interactions...

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Buffer and Noncovalent Interactions Practice Problems 1. What is the final pH of a solution made by mixing 100 ml of 0.05 M acetic acid and 100 ml of 0.1 M sodium acetate? Assume the pK a for acetic acid is 4.76. 2. Describe the preparation of 1000 ml of a 0.2 M acetate buffer pH 5. Assume the pK a of acetic acid is 4.76. 3. Describe the preparation of 1000 ml of a 0.1 M phosphate buffer pH 7.2 starting with 0.5 M H 3 PO 4 and 0.5 M NaOH. Assume the following pK a s: H 3 PO 4 H 2 PO 4 - = 2.2; H 2 PO 4 - HPO 4 -2 = 6.8; HPO 4 -2 PO 4 -3 = 12.4. 4. For a solution that is 0.08 M K 2 HPO 4 and 0.12 M KH 2 PO 4 , calculate the concentrations of H 3 PO 4 , H 2 PO 4 - , HPO 4 -2 , PO 4 -3 ; H + , OH - , and K + . Use the pK a s given above. 5. Match the letter of the interaction ( indicated by ::::: ) to the number giving the correct description of the interaction: A. CH 3 CH 2 NH 3 + ::::: - OC(O)CH 2 CH 3 ______ 1. Ion-Dipole B. CH 3 CH 2 NH 3 + ::::: O=(CH 2 ) 2 ______ 2. Hydrogen Bond C. H-O-H ::::: O=(CH 2 ) 2 ______ 3. Ion-Ion 6. At an air-water interface amphipathic molecules are aligned A. With the hydrophobic tail in the water and the polar head group in the air B. With the polar head group in the water and the hydrocarbon tail in the air. C. Amphipathic molecules are freely soluble in water and do not accumulate at the air-water interface. 5. The pK a for a typical long chain fatty acid is about 5.0. Explain why long chain fatty acids can form micelles in solutions whose pH is greater than 7, but are insoluble in solutions whose pH is
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This note was uploaded on 09/24/2011 for the course CHEM 369 taught by Professor Wang during the Spring '11 term at University of Houston.

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BufferNoncovalentEQ-1 - Buffer and Noncovalent Interactions...

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