How are basic salts formed?

Basic salts are chemical compounds formed by the partial neutralization of a base by an acid. In other words, a basic salt is formed when a base reacts with an acid, but the reaction is not complete. As a result, basic salts still contain some unreacted base, making them slightly basic in aqueous solutions.

Basic salts are formed through a type of chemical reaction called an acid-base reaction. In an acid-base reaction, an acid donates a proton (H+) to a base, which accepts it. When a base reacts with an acid incompletely, meaning not all the base molecules have accepted protons, a basic salt is produced. The resulting basic salt will have a positive ion (cation) from the acid and a negative ion (anion) from the base.

The general equation to represent the formation of a basic salt is: $$ AB + HX \rightarrow AH + BX $$ Here, AB represents the base, HX represents the acid, AH represents the basic salt, and BX represents the byproduct of the reaction.

Let us consider the formation of a basic salt through the reaction of sodium hydroxide (NaOH) with hydrochloric acid (HCl): $$ NaOH + HCl \rightarrow NaCl + H_2O $$ In this reaction, sodium hydroxide (a base) reacts with hydrochloric acid (an acid) to form sodium chloride (NaCl) and water (H2O). Sodium chloride is a neutral salt, not a basic salt. However, if the reaction is incomplete and some sodium hydroxide remains unreacted, the resulting salt will be a basic salt. One example of a basic salt that could be formed in this situation is sodium bicarbonate (NaHCO3): $$ 2NaOH + H_2CO_3 \rightarrow Na_2CO_3 + 2H_2O $$ Here, sodium hydroxide reacts with carbonic acid (H2CO3) to form sodium carbonate (Na2CO3) and water. Note that in certain cases, the term "basic salt" is also used to refer to salts that can hydrolyze in water to produce a basic solution, such as sodium carbonate in the example above: $$ Na_2CO_3 + H_2O \rightarrow 2 NaOH + H_2CO_3 $$ In this case, sodium carbonate dissociates in water to produce a small amount of sodium hydroxide and carbonic acid, generating a basic solution.