The meeting of vinegar and barium hydroxide
In the past, there are those who are good at studying material changes. One day, take acetic acid and put it in a container. The acetic acid has an acidic taste and is weakly erosive, and can be separated into ions in water. And prepare a barium hydroxide solution, which is alkaline, and the dissolved water is scattered into barium ions and hydroxide ions.

When acetic acid is slowly poured into the barium hydroxide solution, at first, the solution is still quiet, not long, and the slight changes are recessive. The hydrogen ion of acetic acid and the hydroxide ion of barium hydroxide quietly merge and turn into water. Barium ions and acetate ions also float in the liquid.

Suddenly, the reaction between the two is gradually intense, the potential for ion interaction is more and more, and the formation of water is more and more. In the solution, the concentration of ions gradually changes, and the conductivity is also different from the initial. After a while, although there is no obvious color change or state change, the microscopic chemical change has reached the depths.

After the reaction is completed, the liquid is mostly barium acetate ions, and excess acetate or barium hydroxide ions. This process shows that the substance is at the microscopic level, and the interaction between ions is wonderful. It is difficult to see the details.