Hydrochloric acid is a strong acid, and finally the hydrogen ions in the liquid basically react. Its velocity should be similar to an arc, the curve is concave, similar to 1/cosx (0, π/2), and the solution is neutral. Acetic acid is a strong base and weak acid salt. Finally, some H ions will remain in the solution, which is acidic, and the curve is similar to hydrochloric acid, but in the end it will not cross the X axis but a straight line that is not equal to Y or 0.