Final answer:
Road salt forms when elements like sodium and chlorine react and undergo an electron transfer to form stable ionic compounds such as sodium chloride. This involves the dissociation of salts in solution when used as deicing agents on icy roads. Various methods can also create salts, including reactions with acids or substitution reactions.
Step-by-step explanation:
When road salt forms, a chemical reaction occurs between the reacting elements, such as sodium and chlorine. Sodium, a highly reactive metal, loses an electron and chlorine, a poisonous gas, gains that electron. This electron transfer results in an ionic bond between the sodium ions (Na+) and the chloride ions (Cl–), forming the ionic compound sodium chloride (NaCl), also known as salt. The process releases a significant amount of light and heat, indicating an exothermic reaction. The resulting salt is stable and unreactive compared to its constituent elements.
When salts like NaCl or CaCl2 are used to deice roads, they must first dissolve and dissociate into their respective ions to lower the freezing point of water, effectively melting the ice. This is an example of a dissociation reaction in solutions. Various salts can also be created by reacting metals more active than hydrogen with the corresponding acids, or by substituting reactions involving soluble salts to prepare insoluble salts.