Final answer:
To derive KD from an equilibrium titration experiment, one would analyze the titration curve at the equilibrium point, use an ICE table for initial and equilibrium concentrations, and the chemical equilibrium expression to calculate the Ka value, which relates to KD.
Step-by-step explanation:
To derive a dissociation constant (KD) from an equilibrium titration experiment, you would analyze the titration curve to determine the equilibrium point where the amount of acid equals the amount of conjugate base.
At the beginning of a titration, the equilibrium for dissociation of a weak acid is significant, described by the equilibrium constant Ka.
When the titration passes the midpoint, the equilibrium involving the conjugate base and water becomes dominant, which corresponds to another equilibrium constant Kb.
The dissociation constant KD and the equilibrium constants Ka and Kb are related to the water dissociation constant Kw, as Kw = Ka × Kb.
An ICE table (Initial, Change, Equilibrium) may be used to organize the initial concentrations, the changes that occur as the reaction proceeds, and the equilibrium concentrations of the reactants and products.
From the ICE table and the balanced chemical equation, you can derive the equilibrium constant expression (Kc) and then calculate the equilibrium constant using the formula
Kc = [products]/[reactants].
In the case of acetic acid, its dissociation in water is summarized with the equilibrium equation CH3CO2H <=> H+ + CH3CO2−, where the Ka can be calculated using the equilibrium concentrations.
To confirm the calculated Ka value, you can use the equilibrium concentrations of H3O+, CH3CO2H, and CH3CO2− to backtrack and ensure the calculated value of K aligns with these concentrations.