C. Determining buffering capacity of phosphoric acid and the Pi buffer
Determining buffering capacity of phosphoric acid
1. Add 25 ml of 50 mM H3PO4 into a 50 ml beaker. Measure the pH.
2. While stirring the solution with a magnetic bar, add 0.2 ml of 1 M NaOH.
Record the pH. Continue the addition of 0.2 ml of 1 M NaOH until the
pH of 11.0 is obtained.
3. Plot the result on a graph with volume of NaOH (in ml) on the x axis and
pH on the y axis.
4. Indicate the pH range when buffer capacity is maximal.