Final answer:
To calculate the pH change when NaOH is added to a buffer, one can use the Henderson-Hasselbalch equation or an equilibrium calculation. An unbuffered solution would experience a substantial pH change upon addition of NaOH, while a buffer solution shows minimal pH variation, highlighting the buffer's role in maintaining pH stability.
Step-by-step explanation:
The question asks to calculate the change in pH when a strong base (NaOH) is added to an original buffer solution. When NaOH is added to the buffer, it neutralizes some of the acid present in the buffer, converting it into its conjugate base. To calculate the pH change, it's necessary to use the Henderson-Hasselbalch equation or perform an equilibrium calculation if the specific components of the buffer (such as acid and conjugate base concentrations) are known.
For an unbuffered solution, the change in pH can be much more significant, as shown by the example of adding 1.0 mL of 0.10 M NaOH to a solution with a pH of 4.74. In this case, the pH is calculated by determining the hydroxide ion concentration (OH-) due to the addition of NaOH, converting that to the pOH, and then using the relation pH + pOH = 14 to find the new pH value.
In contrast, a buffer solution resists changes in pH, so adding a small amount of strong base or acid will result in a minimal change in the pH of the solution, as evidenced by the pH change from 4.74 to 4.75 in the buffer solution. The enormous difference between the pH changes in buffered and unbuffered solutions illustrates the buffer's ability to maintain pH stability.