Ontario Operator-in-Training (OIT) Practice Exam

How are salts formed in chemistry?

1. Through the evaporation of water

2. By reaction between an acid and a base

3. By mixing two solvents

4. Through oxidation reactions

The correct answer is: By reaction between an acid and a base

Salts are formed primarily through the reaction between an acid and a base, a process known as neutralization. During this chemical reaction, the hydrogen ions (H⁺) from the acid combine with the hydroxide ions (OH⁻) from the base to produce water (H₂O), while the remaining ions from the acid and base combine to form the salt. This reaction not only neutralizes the properties of the acid and base but also generates a salt, which is an ionic compound consisting of positively charged ions (cations) and negatively charged ions (anions). The other choices do not accurately describe the formation of salts. For instance, evaporation of water can concentrate ions in a solution, but it does not directly lead to the creation of a salt without the necessary acid-base reaction. Mixing two solvents typically results in a blend of the solvents without any acid-base reaction taking place, and oxidation reactions involve the transfer of electrons rather than the specific interactions between acids and bases necessary to form salts. Thus, the process of acid-base neutralization remains the defining method of salt formation in chemistry.