In: Chemistry
At half -equivalence point [A-] = [HA]
PH = PKa + log[A-]/[HA]
PH = PKa
At half -equivalence point PH = PKa
Pka = PH
PKa = 3.15
-logKa = 3.15
Ka = 10^-3.15 = 0.0007 = 7*10^-4 >>>>>answer
A solution which resists PH value by the addition of small amount of strong acid and strong base is called buffer solution.
They are two types
Acid buffer solution : Acid buffer solution is a mixture of weak acid and it's salt with strong base.
CH3COOH + CH3COONa
Basic buffer solution : Basic buffer solution is a mixture of weak base and it's salt with strong acid.
NH3 + NH4Cl