Calculate the pH of a mixture of one mole of benzoic acid and two mole of sodium benzoate dissolved in 1 L of solution. The pKa of benzoic acid is 4.2. What is the final molar concentration of the buffer?
pH = pKa + log (base)/(acid)
(acid) = mols benzoic acid/1 L = ?
(base) = mols sodium benzoate/1 L = ?
Substitute and solve for pH.
Final concentration of buffer = total mols/total L = mols acid + mols base/total mols = 3 mol/L = ?posted by DrBob222