Even though they have the same concentration they have different pH.
The pH of a strong base is determined by the pOH= -log10(OH-) Where the brackets correspond to molarity. Eg. Calculate the pH of 0.15 NaOH (Sodium hydroxide) solution. pOH= -log10(0.15) pOH= 0.82 Now you need to find pH of the base knowning that pOH + pH = 14 therefore -> 0.82 +pH = 14 pH = 13.18 of NaOH In weak bases we find the (OH-) value by square rooting Kb multiplied by Mb where Mb is the molarity of the base and Kb is a value given for the dissociation constant of a weak base.
Eg. Ammonia is a weak base (as it does not accept protons (H+) easily) calculate the pH of ammonia if the molarity of NH3 is 0.15 moles/litre and the Kb is 1.8×10^-5.
Therefore these bases differ due to different pH also weak bases are poor proton acceptors and strong bases are good proton acceptors. Hope this helps :).
