# q3ps10key - 1. If you were to mix the following solutions,...

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1. If you were to mix the following solutions, which one would result in a buffer? a. 5 mL of .1 M hydrochloric acid and 10 ml of .04 M formic acid b. 5 mL of .01 M sodium hydroxide and 10 ml of .01 M sodium formate c. 10 mL of .01 M hydrochloric acid and 20 ml of .005 M sodium formate d. 10 mL of .01 M sodium hydroxide and 10 ml of .1 M formic acid. Mixing a weak acid and a strong acid will not give you a buffer, so A is out. B is a mixture of strong and weak bases, so it's out too. In option C, the strong acid completely neutralizes the weak base to give a weak acid solution. In D, the strong base will only neutralize some of the weak acid, leaving a buffer solution. 2. If 10 mL of .1 M oxalic acid is added to 200 mL of .5 M sodium oxalate, the final pH of a solution of the solution is 6. What is the pKa of oxalic acid? a. 10 -4 b. 10 -5 c. 4 d. 5 [H +] = 10 -pH = 10 -6 [H + ] = Ka (C a /C b ) Ka = [H + ](C b /C a ) = 10 -6 ([.2 * .5]/[.01 * .1]) = 10 -4 Note: you do not have to account for the liters of solution because they cancel out. pKa = -log K

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## This note was uploaded on 09/12/2010 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.

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q3ps10key - 1. If you were to mix the following solutions,...

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