Answer:
pH = 4.79
Explanation:
The pH of the acetic buffer can be determined using H-H equation:
pH = pKa + log [A⁻] / [HA]
Where pKa is -logKa = 4.76
pH = 4.76 + log [sodium Acetate] / [Acetic Acid]
Where [] can be taken as moles of each specie.
Thus, to find pH of the buffer we need to calculate molesof acetic acid and sodium acetate.
Initial moles:
Initial moles of acetic acid and sodium acetate are:
500mL = 0.500L ₓ (0.60moles / L) = 0.30 moles of both acetic acid and sodium acetate
Moles after reaction:
Now, 0.010 moles of NaOH are added to the buffer reacting with acetic acid, CH₃COOH, producing more acetate ion, as follows:
NaOH + CH₃COOH → CH₃COO⁻ + H₂O
That means after reaction moles of both species are:
Acetic acid: 0.30mol - 0.010mol (Moles that react) = 0.29 moles
Acetate: 0.30mol + 0.010mol (Moles produced) = 0.31 moles
Replacing in H-H equation:
pH = 4.76 + log [0.31] / [0.29]
