2. Using the Henderson-Hasselbalch equation.
2.1 Calculate the molar proportion of Na2HPO4 and KH2PO4 needed to
give a solution of pH 6.5.
2.2 Using this figure, make up a measured volume of0.15M phosphate
solution and read the pH.
2.3 Dilute the solution 10 times and read the pH once more.
3. Determining buffering capacity of phosphoric acid and resulting Pi buffer.
3.1 Take 25ml of 50mM H3PO4 into a 50ml beaker.
3.2 Stir the solution with a magnetic flea and read the pH.
3.3 Add 0.2ml portions of 1M NaOH (approximate) mixing well and
reading the pH after each addition.
3.4 Plot the result on a graph with volume of NaOH on the ―x axis and
pH on the y axis.