Hello!
A solution of a weak acid and its conjugate base is called a buffer solution. It can resist the addition of bases and acids while maintaining the pH approximately constant.
To calculate the pH of a buffer solution, we'll use the famous Henderson-Hasselbach equation, applying the pKa value of the Benzoic Acid (4,20). In this equation, [A⁻] represents the concentration of the Conjugate Base and [HA] the concentration of the acid.
[tex]pH=pKa + log( \frac{ [A^{-}]}{[HA]} ) \\ \\ pH=4,20 + log ( \frac{0,170 M}{0,245} ) \\ \\ pH=4,04 [/tex]
So, the pH of the solution would be 4,04.
Have a nice day!
