Answer:
pH of the solution is 3.70
Explanation:
The given weak acid (HA) and it's sodium salt (NaA) forms a buffer system. According to Henderson-Hasselbalch equation for this buffer system-
[tex]pH=pK_{a}+log(\frac{n_{A^{-}}}{n_{HA}})[/tex]
Where, [tex]n_{A^{-}}[/tex] and [tex]n_{HA}[/tex] represent number of moles of [tex]A^{-}[/tex] ion and HA respectively.
Here [tex]\frac{n_{A^{-}}}{n_{HA}}=2[/tex] and [tex]pK_{a}=-logK_{a}=-log(4.0\times 10^{-4})=3.40[/tex]
So, [tex]pH=3.40+log2=3.70[/tex]
Hence pH of the solution is 3.70
