Polyprotic Titrations and Buffers

            
             The purpose of this experiment was to prepare two buffer solutions in order to observe a change in the pH when various solutions we added. A buffer is defined as a solution that contains a substantial amount of a weak acid and its conjugate base. An acid-base equilibrium that keeps the pH stable despite addition of moderate quantities of strong acid or base must be present in order for a solution to function as a buffer. Buffer capacity can be described as how well a buffer can resist change in pH. In part two of this experiment, it was concluded that different solutions have dissimilar buffer capacities. For example, deionized water and a highly concentrated acid-base solution have significantly different buffer capacities. The buffer capacity of a highly concentrated solution is much higher than that of a less concentrated solution of the same acid and base.
             Data and Observations:.
             Part 2: Buffer Solutions.
             Data Table 1: Preparation of Buffer Solutions 1 and 2.
             Buffer Solution 1.
             Buffer Solution 2.
             Mass KH2PO4 (g).
             2.720.
             679.
             Mass K2HPO4 (g).
             3.478.
             058.
             Initial pH.
             6.73.
             5.28.
             Data Table 2: Testing Deionized Water.
             Initial pH of 100mL Deionized Water.
             6.75.
             pH after addition of two drops of 0.1M HCl.
             3.18.
             pH after addition of an additional two drops of HCl.
             3.03.
             pH after addition of an additional two drops of HCl.
             2.91.
             Data Table 3: Testing Buffer Solutions 1 and 2.
             Dropper 1 pH.
             Dropper 2 pH.
             2 Drops.
             6.69.
             5.34.
             2 Drops.
             6.68.
             5.30.
             2 Drops.
             6.68.
             5.18.
             1 Dropper.
             6.64.
             3.17.
             1 Dropper.
             6.61.
             2.77.
             38 Droppers.
             3.51.
             ----------.
             Observations: Drops contain 0.1M HCl. One dropper contains approximately 25-26 drops.
             Results:.
             Results Table 1: Buffer Solutions.
             pKa.
             7.16.
             Theoretical pH of Buffer 1.
             7.16.
             Theoretical pH of Buffer 2.
             5.98.
             Calculations:.
             Theoretical pH of Buffer 1.
             pH : how acidic/basic a solution is.
             pKa : indicator of hydrogen acidity.
             *The data for this calculation was taken from Data Table 1.
             Theoretical pH of Buffer 2.
             pH : how acidic/basic a solution is.
             pKa : indicator of hydrogen acidity.