Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What is the key characteristic of a double replacement reaction?

1. One reactant replaces another reactant

2. Two compounds exchange ions

3. A compound is synthesized from elements

4. Energy is absorbed to break bonds

The correct answer is: Two compounds exchange ions

A double replacement reaction is characterized by the exchange of ions between two compounds. In this type of reaction, two ionic compounds react in solution, leading to the formation of two new products as the cations and anions swap partners. This can often be observed in reactions resulting in precipitate formation, gas production, or the creation of a weak electrolyte like water. The essence of this reaction lies in the interaction between the ions of the original compounds, which allows them to form new compounds. This distinguishes double replacement reactions from other types of reactions, such as single replacement, synthesis, or decomposition, which involve different mechanisms of reactant transformation and bond breaking or forming processes. Understanding this characteristic is crucial for identifying double replacement reactions in various chemical scenarios, such as in acid-base neutralization or precipitation reactions.