Question

Sodium Phosphate buffer has 3 ionizable groups, with pKa's of 2.15, 7.20 and 12.45. A 1.00 M solution of this buffer (200 mL) is found to have a pH of 7.50 A biochemist adds 30.0 mL of 1.00 M HCL to this buffer.

(a) How many moles of Na2HPO4 and NaH2PO4 are present before the addition of HCl?

(b) What is the resultant pH after the addition of HCL?

(C) How many total milliliters of 0.350 M NaOH can you add to the final solution in Question 8b and still maintain as a good phosphate buffer (i.e. within 1 pH unit of pKa).