24. In a double replacement reaction, which of the following occurs?
Answer: C
A gas, solid precipitate, or compound forms in the exchange of ions.
In a double replacement reaction, the most characteristic occurrence is the formation of a gas, solid precipitate, or a new compound as the ions in the reactants exchange partners. This process is essential to the definition and understanding of double replacement reactions.
A) Energy in the form of heat or light is often produced.
While it is true that some reactions may release energy in the form of heat or light, it is not a defining characteristic of double replacement reactions. This option is more commonly associated with exothermic reactions, which can occur in various types of reactions, not specifically limited to double replacement.
B) The reactants are usually a metal and a nonmetal.
This statement is incorrect for double replacement reactions as they typically involve two ionic compounds, which may consist of combinations of metals and nonmetals. Therefore, describing the reactants as usually being a metal and a nonmetal does not accurately reflect the nature of double replacement reactions.
C) A gas, solid precipitate, or compound forms in the exchange of ions.
This option accurately describes the primary outcome of double replacement reactions, where ions from two different compounds exchange partners to form new products, which may include gases, solid precipitates, or new compounds. This exchange is a fundamental aspect of double replacement reactions.
D) All statements are true.
This option is incorrect because not all previous statements (A and B) are true. Since both A and B do not accurately describe double replacement reactions, it cannot be concluded that all statements are true. Thus, this choice is invalid.
Conclusion
The correct answer, C, is definitive as it accurately encapsulates the core process of double replacement reactions, which is the exchange of ions leading to the formation of new products. All other options fail to either fully describe the reaction or mischaracterize the nature of the reactants involved, reinforcing that C is the only valid statement regarding double replacement reactions.