Answer Happy

1. to prepare the phosphate buffers. solutions from a stock solution, use Eqn 7bn-7.
2. to prepare the phosphate buffers from solid NaH2PO4.2H2O and solid Na2HPO4.2H2O, use Eqn 7b-8, Eqn 7bn-9, and Eqn 7b-10.
Table 7b-2. pH change. COM Parameters Samples 0.050 M phosphate buffer Distilled water 6.65 pH before addition of NaOH pH after addition of NaOH pH before addition of HCI pH after addition of HCI 6.71 9.48 6.54 4.02 0.0050 M phosphate buffer 6.48 6.57 6.35 6.21 6.71 6.30 6.25 Table 7b-3. Buffer capacity. Parameters Volume of phosphate buffer, mL Initial pH Final pH Final buret reading (Vt), ml Initial buret reading (Vi), mL Samples 0.050 M phosphate buffer 0.0050 M phosphate buffer 35.0 35.0 6.31 6.52 7.31 7.52 42.10 42.80 35.00 42.10 Preparation of Buffers 1. To prepare the phosphate buffers solutions from a stock solution, use Eqn 7b-7. CiV1 = C2V2 (Eqn 7b-7) 2. To prepare the phosphate buffers from solid NaH2PO4-2H20 and solid Na2HPO4-2H20, use Eqn 7b-8, Eqn 7b-9, and Eqn 7b-10.

Preparation of Buffers 1. To prepare the phosphate buffers solutions from a stock solution, use Eqn 7b-7. CiV1 = C2V2 (Eqn 7b-7) 2. To prepare the phosphate buffers from solid NaH2PO4-2H20 and solid Na2HPO4-2H20, use Eqn 7b-8, Eqn 7b-9, and Eqn 7b-10. [A] pH = pka + log [HA] (Eqn 7b-8) no. of moles of component mole fraction of component = total no. of moles (Eqn 7b-9) mass of component = (Mbuffer)(Vbuffer)(MMcomponent)(mole fraction component) (Eqn 7b-10)