in the picture, the acid is titrated with alkali. The sudden rise of the curve is expressed as words: with the dripping of NaOH solution, the pH value suddenly rises rapidly around pH7 (that is, the solution is neutral), and the rising speed drops sharply when it reaches about 12.

explanation: the calculation method of the pH value of the solution is the negative logarithm of the hydrogen ion concentration. At the initial stage of titration, the hydrogen ion concentration is relatively high, and the neutralization amount of NaOH solution to hydrogen ion is very small relative to the total hydrogen ion concentration, while near pH7, the hydrogen ion concentration is close to the hydroxide ion concentration, and the dripping hydroxide ion has a great influence on the pH value of the solution, which is reflected in the pH curve, that is, the titration curve near pH7 is steeper and changes more suddenly.