Humber Admissions Practice Test

What type of chemical reaction occurs when two compounds exchange ions or atoms resulting in the formation of a gas, solid precipitate, or molecular compound?

1. Oxidation Reaction

2. Double-Displacement Reaction

3. Combustion Reaction

4. Synthesis Reaction

The correct answer is: Double-Displacement Reaction

The process described involves two compounds undergoing a transformation where they exchange ions or atoms. This type of reaction is characteristic of double-displacement reactions, which are also known as metathesis reactions. During these reactions, the components of the reactants switch partners, leading to a new arrangement of ions. A defining feature of double-displacement reactions is their potential to produce a gas, a solid precipitate, or a molecular compound as one of the products. For instance, when an aqueous solution of silver nitrate reacts with sodium chloride, they exchange ions to form sodium nitrate and solid silver chloride, which precipitates out of the solution. This distinguishes double-displacement reactions from other types, such as oxidation reactions, which involve the transfer of electrons and changes in oxidation states, or combustion reactions, which primarily involve the rapid reaction of a substance with oxygen to produce heat and light. Synthesis reactions, on the other hand, typically involve the combination of simpler substances to form a more complex compound, rather than exchanging components between two compounds. Thus, the correct identification of double-displacement reactions is key to understanding the dynamics of chemical interactions involving ionic compounds.