Lab #9 Purpose: The purpose of this lab is to find values of acid ionization constants by measuring the pH. Also we learn to prepare buffer solutions and observe their resistance to pH change. Procedure: In part I we found K a of acetic acid by using a pH meter to find the titration curve and compared it to the correct K a , 1.76E-5. We found the K a to be 2.0*10E-5. Errors could have been caused by not adding 1mL at a time but instead adding a little over or under each time. This error would have thrown off the ability to tell when the pH was increasing rapidly, thus changing the mLs needed to reach the half equivalence point and equivalence point. For part II we found the dissociation constant of acetic acid in different solutions. First we had 10mL of acetic acid, and found the K a to be 1.00317E-5. This error could be attributed to an error in the pH meter. When 25mL of NaA were added to 10mL of acetic
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- Winter '08