does the addition of a strong acid increase the percent ionization of a weak acid HB?
To determine how the addition of a strong acid affects the percent ionization of a weak acid, you need to consider the concept of common ion effect.
When a strong acid is added to a solution of a weak acid, it increases the concentration of hydrogen ions (H+) in the solution. This increased concentration of H+ ions shifts the equilibrium of the weak acid towards the ionized form since the reaction proceeds in the direction that reduces the excess of H+ ions.
By Le Chatelier's principle, the shift towards the ionized form of the weak acid would result in an increase in the percent ionization of the weak acid, as more molecules of the weak acid will dissociate into their constituent ions.
To calculate the new percent ionization, you will need to know the initial concentration of the weak acid and its degree of ionization. You can then compare this with the concentration of the weak acid after the addition of the strong acid to determine the effect on percent ionization.
Here's a step-by-step procedure to calculate the percent ionization of a weak acid after the addition of a strong acid:
1. Determine the initial concentration of the weak acid HB and its degree of ionization (α) using experimental data or given information.
2. Calculate the initial concentration of the hydronium ions (H3O+) from the weak acid's degree of ionization: [H3O+] = α * [HB].
3. Determine the concentration of the strong acid being added.
4. Consider the reaction between the strong acid and water: strong acid (HA) + H2O ⇌ H3O+ + A-
5. Calculate the concentration of the hydronium ions (H3O+) contributed by the strong acid, based on its initial concentration.
6. Add the concentration of hydronium ions contributed by the weak acid (from step 2) to the concentration of hydronium ions contributed by the strong acid (from step 5) to get the total concentration of H3O+ in the solution after the addition of the strong acid.
7. Calculate the new concentration of the non-ionized form of the weak acid HB' using the conservation of mass: [HB'] = [HB] - [H3O+].
8. Calculate the new degree of ionization (α') of the weak acid in the presence of the strong acid: α' = ([H3O+]/[HB]) * 100.
9. Calculate the new percent ionization of the weak acid HB in the presence of the strong acid: percent ionization = α' * 100.
By following these steps, you can determine how the addition of a strong acid affects the percent ionization of a weak acid.
No, just the opposite; it decreases it.
HB <===> H^+ + B^-
Ka - (H^+)(B^-)/(HB)
Now if we add a strong acid, such as HCl, notice that is a common ion (the H^+ ion) so by Le Chatelier's Principle, the reaction is shifted to the left (in order to try to undo what has just been done); i.e., H^+ has been added so it tries to remove it and the only way that can happen is for it to move some of the ionized H^+ back to the unionized form. Voila!. More of the unionized form and less of the ionized form means a lower percent ionization.