Explain why the pH at the stoichiometric point of a weak acid titrated with a strong base is always greater th?

when treating a weak acid with a strong base ..you are geenrating water plus the conjugate base of the weak acid. According to Bronsted/Lowry theory, weak acids yield strong conjugate bases which means in a water solution the conjugate base will hydrolyze to produce small amounts of OH wich will raise the pH over 7..For example the weak acid acetic acid ( HOAc ) reacted with the stoichiometric amount of NaOH will yield water and sodium acetate .
The acetate will hydrolyze in tthe water like so
AcO^-1 + H2O--------->  HOAc  + OH^-1  the Kh for this reaction is
10^-14/1.75 X 10^-5 = 5.71 X 10^-10 which when solved for
the small amount ( X ) of hydroxide produced yields a pH around 8ish.

For a strong acid and strong base the pH will be 7 because the conjugate base of a strong acid is a weak base and cannot hydrolyze ( cannot compete with OH for protons ) ..as a consequence the pH is derived from the only source of hydrogen ions , water ( pH = 7 )