When 0.025 moles of HCl are added to 325 mL of a buffer solution. The pH of the buffer solution after adding 0.025 moles of HCl will be 13.85.
What is the pH of the buffer solution?
Initial concentrations of HF and F- in the buffer solution:
[H+] = [HF] = 0.620 M
[OH-] = [F-] = 0.710 M
Change in concentration of HF and F- after adding HCl:
[H+] = [HCl]
[H+] = 0.025 moles / 0.325 L (325 mL = 0.325 L)
= 0.077 M
New concentration of HF is:
[HF] = 0.620 M - 0.077 M
= 0.543 M
The concentration of F- remains the same.
pOH of the solution:
pOH = -log [OH-]
= -log (0.710)
≈ 0.150
pH of the solution:
pH + pOH = 14
pH = 14 - pOH
≈ 14 - 0.150
≈ 13.85
Therefore the pH of the buffer solution after adding 0.025 moles of HCl will be 13.85.