Question

When the Sorensen’s buffer was prepared, equal amounts of the acid and base forms of the buffer system should have been present. However, you likely found that the pH was not equal to the pKa of the buffer. What likely caused this discrepancy?

Answer 1

1. May be doubly deionized water is not used (since tap water has several minerls), it will contaminate the buffer system. This buffer tends to form precipitates in presence of calcium ions.

2. The selection of hydrated salts is not correct like (Na₂HPO₄*2H₂O , Na₂HPO₄*7H₂O, Na₂HPO₄*12H₂O)

3. Becomes slowly contaminated with micro-organisms, affects pH

4. Although pH changes little with temperature. But higher temperature leads to change the ionic equilibrium and effects the pH of the buffer.

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