Question

Post-lab Questions 1. (2pts) Another buffer found in blood is based on the equilibrium between dihydrogen phosphate and monohydrogen phosphate. The reaction is shown below: H2PO (a)+H2o H,O* (a) НРО, ) -2 + If the pH of a blood sample was 7.35, what would you calculate as the ratio of [H,PO ] to (HРО, 3) (K = 7.5 X 10, K = 6.2 X 10-, Kg 3.6 X 10~13) Pha-toma6oe 7.257.21+10HPO4/HaPOu 2. (4 pts) If you needed to performa reaction in a controlled pH environment that was fairly basic, you might choose to use the ammonium and ammonia buffer system. How many grams of solid ammo- nium chloride would you have to add to 1.250 liters of 0.165M NH, to obtain a buffered solution of pH= 8.85 8.85-9.85 laD6-) (K, of NH, = 1.8 X 10-5)

Answer 1

your approach is fine. 28. 7.35 = 1.21 tlog ( Poto) -log 72m2.95 Hap og Holoa - 0.14 100.72 не ол & for Milly + Noace butter system, por = pk + log ( Herace | 4.74 let nmole Mug Cd is added por= - 4.79 14- Pro 14-8-85 - 5.15 5:15 - 4.74 +log Connessing) lock - S.15-4.74 0. 20625 0.4) 0-20625x2.57 = 0.53 Mole mass of Nhacd = 0.534 molar mass 0.534 53.5 - 28.35 g