Weak base protonation

[Nataly Antonova 1B]

Why is it that when calculating the weak base protonation percentage, the equation is ? I remember doing a similar calculation with acid, and the equation was
What exactly is the difference there and why do we include the term [BH+] in the denominator of the first calculation?
Thank you!

[Jose Angelo Grajeda 2D]

I believe both equations are similar, in that % protonated is just the equilibrium concentration of the conjugate acid [BH+] (what was protonated) over the initial concentration of the base: [B] initial, times 100. % ionized is the same thing but opposite: the equilibrium concentration of the conjugate base [A-] over the initial concentration of the acid ([HA] initial), times 100. The bottom of the first equation looks different, but it should equal the same thing!

[B] initial = [B] equilibrium + [BH+]. In other words, the original base concentration equals the [B] at equilibrium PLUS the change concentration [BH+], because that was subtracted from the initial conc. of [B] to get to equilibrium. Therefore, % protonated = ([BH+]/[B] initial) * 100 , which also = ([BH+]/[B] equilibrium + [BH+]) * 100. Hope this helps!