Percentage Protonation

[Quinton Sprague 1A]

Wondering if anyone could help me calculate this, looked in my notes but can't figure it out. I see on Sapling that you are supposed to use the formal concentration for the reactant, does this mean initial or final? Is the equation essentially concentration of H+/OH- divided by the concentration of the reactant?

[Katie Nye 2F]

Generally, when dealing with Ka and pH and all those other values, the concentration that you need is the concentration at equilibrium! The initial concentration is vital to solve for the change and the final but most equations need the equilibrium concentrations.

[Varsha Ravi 3E]

When you're solving for percentage protonation, you divide the equilibrium concentration of the (product) conjugate (base or acid) by the initial concentration of the (reactant) acid or base).