Determine how many moles of h3o+ can be neutralized

Question

Consider a buffer solution that contains 0.50 MNaH₂PO₄ and 0.20 MNa₂HPO₄.
a. Calculate the pH of this buffersolution.

b. Calculate the pH after 0.120 g ofsolid NaOH is added to 150 mL of this buffer solution.

c. If the acceptable buffer range ofthe buffer solution is ± 0.10 pHunits, calculate how many moles of H₃O⁺ canbe neutralized by 250 mL of the buffer.