Humber Admissions Practice Test

Which of the following best describes the process of a double-displacement reaction?

1. The breaking down of a compound into simpler substances.

2. The formation of water from hydrogen and oxygen.

3. The exchange of components between two ionic compounds in a solution.

4. The combination of two or more substances to form one product.

The correct answer is: The exchange of components between two ionic compounds in a solution.

The process of a double-displacement reaction is accurately described as the exchange of components between two ionic compounds in a solution. In this type of reaction, the cations and anions of the reactants switch partners, forming two new compounds. Typically, this occurs in aqueous solutions where the compounds can disassociate into their ions. For example, when mixing solutions of silver nitrate and sodium chloride, the silver ions (Ag+) will combine with chloride ions (Cl-) to form silver chloride, a solid precipitate. Meanwhile, sodium ions (Na+) will combine with nitrate ions (NO3-) to form sodium nitrate, which remains dissolved in the solution. This mechanism distinguishes double-displacement reactions from other types of reactions. Unlike decomposition reactions, which refer to breaking down compounds into simpler substances, or synthesis reactions, where multiple reactants combine to form one product, double-displacement specifically involves the swapping of ions between two compounds. Therefore, the correct identification of this process contributes to a deeper understanding of chemical reactions and their behaviors in various contexts.