Free Essay On General Chemistry Lab

pH AND BUFFERS report

Part 1:

Solution A is a buffer solution with a very low buffer capacity. The reason for the buffer is that CH3COOH being a weak acid can easily release H+ ion, which reacts with CH3COONa to form CH3COOH in solution.
As seen from the chart 1, when sodium hydroxide (NaOH) was added to the buffer solution A, the PH value of the buffer solution changed at a slower pace at the beginning indicating that H+ ion was released by CH3COOH in the solution. This release of hydrogen ion delayed the change of PH value. On the other hand, when there was the little volume of CH3COOH in the solution, the addition of 3ml NaOH lead to the sudden change of PH to a very high level.
On contrary to chart 1, the chart 2 shows that there was a big and quick change in PH value of the solution at first, and then the change slows down. The reason for this was that the solution contained CH3COO- ion in it, which reacts with the hydrogen ion formed in the solution quickly to form CH3COOH making the solution more acidic.

Part 2:

The chart 3 shows that when the 3 ml NaOH was added to the solution, the PH value of the solution changed slowly, and this change was fast at the later period because with the passage of time the CH3COOH acid was ionized leaving the small volume of CH3COOH present in the solution.
According to the chart 4 given, the PH value fell slowly first because the presence of CH3COO- made it a buffering solution. With the passage of time, once 4.5 ml of HCL was added to the solution, the PH of the solution changed rapidly because most of the CH3COONa was consumed in the reaction.

Part 3:

In the part, 3 of the experiment, when the 4 drops of NaOH was added to the solution, the PH of the solution reached 11. This showed the linear change in the PH of the solution. Without the presence of the buffer, the H+ ions present in the solution reacted with OH- ions coming from NaOH and this change the PH of the solution linearly.