Final answer:
Adding 7.00 mL of 0.100 M HCl to the buffer solution will result in a change in pH of approximately 0.06. When 7.00 mL of 0.100 M NaOH is added to the buffer solution, the change in pH can also be calculated using the Henderson-Hasselbalch equation.
Step-by-step explanation:
When 7.00 mL of 0.100 M HCl(aq) is added to 100.0 mL of a buffer solution that is 0.100 M in NH3(aq) and 0.100 M in NH4Cl(aq), the change in pH can be calculated using the Henderson-Hasselbalch equation:
pH = pKa + log ([A-]/[HA])
In this case, the acid is NH4+ and the base is NH3. The pKa value for NH4+/NH3 is known to be approximately 9.25. Using the equation and plugging in the values, we can calculate the change in pH to be approximately 0.06.
When 7.00 mL of 0.100 M NaOH is added to the original buffer solution, the change in pH can be calculated in a similar way. Since NaOH is a strong base, it will react with the weak acid in the buffer solution, NH4+. The resulting NH4OH formed will cause an increase in the concentration of NH3, resulting in a change in the ratio of [A-]/[HA]. This change will lead to a change in pH. To calculate the change in pH, you can use the Henderson-Hasselbalch equation again, but this time with the new concentration of NH3.
Since the calculations involve the Henderson-Hasselbalch equation, you will need to know the pKa value of NH4+/NH3 and apply the equation using the given concentrations of the buffer components. The calculation for the change in pH when adding 7.00 mL of 0.100 M NaOH to the buffer solution can be done in a similar way as for the addition of HCl.