What Kind of Acid, Base or Buffer Problem is It, Anyway?

1.  Is it a strong acid or base?
    a.  Strong acid, use pH = -log [H₃O⁺]
    b.  Strong base, use pOH = -log [OH-], then 14-pOH = pH

2.  Is is a weak acid?  
     a.   Is only the weak acid [HA] present?  Then use Ka = x²/ [HA] with  x = [H₃O⁺] and pH = -log [H₃O⁺]  (ICE method)
     b.   Are both the weak acid and its conjugate base present, or is this a buffer solution?  Then use the Henderson-Hasselbalch equation.
           pH = pKa + log [A-]/[HA]

3.  Is it a conjugate base?  e.g. Sodium acetate, potassium formate etc
     Use Kb = [HA][OH-]/[A-]==>  Kb x Ka = 1 x 10¹⁴ ==>  Kb = x²/[A-] with x = [OH-] and pOH = -log [OH-], then 14-pOH = pH

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