Answer:
Step-by-step explanation:
To calculate pH you need to use Henderson-Hasselbalch formula:
pH = pka + log₁₀
![([A^-])/([HA])](https://img.qammunity.org/2020/formulas/chemistry/college/awhrxc2bq91k57agvv2u931h8oo4ur1uwf.png)
Where HA is the acid concentration and A⁻ is the conjugate base concentration.
The equilibrium of acetic acid is:
CH₃COOH ⇄ CH₃COO⁻ + H⁺ pka: 4,75
Where CH₃COOH is the acid and CH₃COO⁻ is the conjugate base.
Thus, Henderson-Hasselbalch formula for acetic acid equilibrium is:
pH = 4,75 + log₁₀
![([CH_(3)COO^-])/([CH_(3)COOH])](https://img.qammunity.org/2020/formulas/chemistry/college/hajxxfz5tbazq65oads7uga2ymn0mhst0t.png)
a) The pH is:
pH = 4,75 + log₁₀
![([2 mol])/([2 mol])](https://img.qammunity.org/2020/formulas/chemistry/college/embd1srexgzyq7uyhmppmj6kjutnunqx9b.png)
pH = 4,75
b) The pH is:
pH = 4,75 + log₁₀
![([2 mol])/([1mol])](https://img.qammunity.org/2020/formulas/chemistry/college/u0n58q9jbx86bkcfkuedsfwa6mgmlrw2i9.png)
pH = 5,05
I hope it helps!