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Unformatted text preview: Sample pH / Buffer Problems Sample pH / Buffer Problems Sample pH / Buffer Problems Sample pH / Buffer Problems Common Biochemical Buffers Common Biochemical Buffers Common Biochemical Buffers Common Biochemical Buffers (These are for your practice. If you can do these, you should be able to do any I give you on the exams.) 1) Starting with solid Tris base base base base and 1M HCl, describe how one would make 2 liters of 200 mM (= 0.2 M) Tris-HCl buffer pH 7.5 (a) We want 2 liters of 0.2 M Tris, MW=121.1 (b) Calc acid / base ratio (c) To get .326 mol of Tris • H, need to add 0.326 liters of 1 M HCl (d) Add H 2 O to 2000 ml 2) Starting with 5 M Phosphoric acid and 10 M NaOH, make 1000 ml of .25 M Na Phosphate buffer Buffer System Buffer System Buffer System Buffer System MW MW MW MW pKa1 pKa1 pKa1 pKa1 pKa2 pKa2 pKa2 pKa2 pKa3 pKa3 pKa3 pKa3 Formic acid (HCOOH) 46.02 3.75 Acetic Acid (CH 3 COOH) 60.04 4.76 Phosphoric (H 3 PO 4 ) 97.97 2.2 6.86 12.4 Carbonic (H 2 CO 3 ) 62.01 6.10 10.22 10....
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- Spring '08
- pH, buffer solution, M Na Phosphate