On the reaction between sodium chloride and lead acetate
and the combination of various substances, there must be a reason. Sodium chloride, the main component of the salt used in daily life, is also peaceful, and can be dissociated into sodium ions and chloride ions in water. Lead acetate, a compound of acetate and lead ions, also has special properties.

When the two meet, according to chemical principles, although lead acetate is a weak electrolyte, when it is mixed with sodium chloride, if it wants to react, it should follow the rules of ion exchange. The chloride ion ($Cl ^ - $) of sodium chloride ($NaCl $) and the lead ion ($Pb (CH_3COO) _2 $) of lead acetate ($Pb ^ {2 + }$）， may try to combine to form lead chloride ($PbCl_2 $). The acetate ion ($CH_3COO ^ - $) and sodium ion ($Na ^ + $) may combine.

However, the nature of lead chloride, although its solubility is limited, it is not completely insoluble in water at room temperature. And lead acetate is a weak electrolyte, and there is ionization equilibrium in the solution. When sodium chloride is added, the ion concentration in the solution changes and the equilibrium is disturbed.

Let the chemical equation for this reaction be: $2NaCl + Pb (CH_3COO) _2\ rightleftharpoons PbCl_2 + 2CH_3COONa $. In this formula, the two-way arrows indicate that this reaction may be reversible. Because lead chloride is not absolutely insoluble, sodium acetate is also a strong electrolyte and is completely ionized in water, so various ions in the solution interact and are in a dynamic equilibrium state.

To make the reaction proceed in the direction of generating lead chloride, the reaction conditions may be changed, such as adjusting the temperature, changing the solution concentration, etc. Increasing the temperature may slightly change the solubility of lead chloride, which in turn affects the reaction equilibrium; or increase the concentration of sodium chloride, according to Le Chatelier's principle, the equilibrium will move in the direction of generating lead chloride, in order to weaken the effect of increasing the concentration of the reactants.

Although the reaction between these two seems simple, the interaction between ions and the movement of equilibrium all contain subtle chemistry, which needs to be explored in detail to understand its true meaning.