Answer:
3.11 is the pH of the buffer
Explanation:
The pH of a buffer is obtained using H-H equation:
pH = pKa + log [Conjugate base] / [Weak acid]
<em>Where pH is the pH of the buffer, pKa = -log Ka = 3.14 for the citric buffer and [] could be taken as the moles of each species.</em>
The citric acid,HX (Weak acid), reacts with NaOH to produce sodium citrate, NaX (weak base) and water:
HX + NaOH → H2O + NaX
That means the moles of NaOH added = Moles of sodium citrate produced
And the resulitng moles of HX = Initial moles - Moles NaOH added
<em>Moles HX and NaX:</em>
Moles NaOH = 0.100L * (0.65mol / L) = 0.065 moles NaOH = Moles NaX
Moles HX = 0.300L * (0.45mol / L) = 0.135 moles HX - 0.065 moles NaOH = 0.070 moles HX
Replacing in H-H equation:
pH = 3.14 + log [0.065mol] / [0.070mol]
pH = 3.11 is the pH of the buffer
