CH 3 COOH (aq) H + (aq) + CH 3 COO - (aq) However, all the calculated dissociation constant values are close to each other and are all slightly above the accepted value, possibly because the higher K a indicates that there was more dissociation of HA. The values of pH calculated differed across the solutions, with the 1.0 M HA solution having a pH of 2.34, the buffer with 25.0mL 1.0M NaA having a pH of 4.95, and the buffer with 5.0mL NaA having a pH of 3.81. The addition of the sodium acetate is not intended to largely change the pH, as that is the intention of a buffer. However, the trend does show that the more sodium acetate is added, the more basic the pH. The measured pH and the calculated
pH for the buffers were very close with errors less than 4%. Both measured pHs are lower than that of the calculated, possibly because the solution was not thoroughly mixed. In part three, a strong base and strong acid were added to a buffered and unbuffered solution. The unbuffered solution showed a huge change in pH when the strong acid and base were added, but the buffered solution showed resistance to change. The measured and calculated
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- Spring '14