What characterizes a double displacement reaction?

A double displacement reaction, also known as a double replacement reaction, is characterized by the process in which two compounds react with one another, resulting in the exchange of ions and the formation of two new compounds. In this type of reaction, the cations and anions from the reacting compounds swap places, leading to the creation of different compounds that may have different properties from the original substances.

For instance, in a classic example of a double displacement reaction, when a solution of sodium sulfate is mixed with a solution of barium chloride, the ions exchange partners to produce barium sulfate and sodium chloride. The newly formed compounds can be either soluble or insoluble in water, which is often a key aspect of driving the reaction forward, especially when a precipitate forms.

The other scenarios presented do not describe double displacement reactions. The breakdown of one compound into its components indicates a decomposition reaction, while reacting a single compound with oxygen that results in heat identifies combustion reactions. Lastly, the rearrangement of multiple reactants that yields the same products does not reflect double displacement mechanics, as it implies no actual exchange of ions has occurred. Thus, option B accurately defines the essence of double displacement reactions.