Final answer:
The final [H+] concentration when 1.00 L of 0.0550 M HCl is mixed with 1.00 L of 12.0 M acetic acid is approximately 0.0550 M, as the strong acid HCl will dominate the acidity of the solution and the contribution of acetic acid can be considered negligible.
Step-by-step explanation:
To calculate the final [H+] when 1.00 L of 0.0550 M HCl is mixed with 1.00 L of 12.0 M acetic acid, we must take into account that HCl is a strong acid and will completely dissociate in solution, contributing 0.0550 M of [H+] ions. On the other hand, acetic acid is a weak acid and its dissociation in water is described by the acid dissociation constant, Ka, which is 1.80 × 10⁻⁵ for acetic acid. However, since HCl is a strong acid and will suppress the ionization of acetic acid by shifting the equilibrium to the left (Le Châtelier's principle), we can consider that the [H+] concentration from the acetic acid will be negligible compared to the concentration from the HCl.
Therefore, the final [H+] concentration in the solution will be approximately equal to the concentration of HCl, which is 0.0550 M. Since the volumes of the two solutions are equal, the final total volume of the mixture will be 2.00 L. Therefore, we do not need to adjust the HCl concentration. As an approximation, we can ignore the contribution of acetic acid to the [H+] concentration in the presence of a strong acid.