- A double-replacement reaction involves two compounds exchanging ions to form two new compounds.
- The general form is \(AB + CD \rightarrow AD + CB\).
- Among the options, \(A + BC \rightarrow B + AC\) is single-replacement, \(A + B \rightarrow AB\) is synthesis, and \(AB \rightarrow A + B\) is decomposition.
- The final answer is \(\boxed{AB + CD \rightarrow AD + CB}\).
Explanation
- Analyzing Chemical Reaction Patterns
A chemical reaction involves the reorganization of atoms to form new substances. To identify a double-replacement (also known as a double-displacement or metathesis) reaction, we look for a specific pattern where two ionic compounds swap their ions. The general form is \(AB + CD \rightarrow AD + CB\), where \(A, B, C, D\) represent ions or components. In this reaction, the cation of the first compound (\(A\)) pairs with the anion of the second compound (\(D\)), and the cation of the second compound (\(C\)) pairs with the anion of the first compound (\(B\)).
- Evaluating the Options
Let's evaluate the provided options:
- \(A + BC \rightarrow B + AC\): This represents a single-replacement reaction, where one element replaces another element in a compound.
- \(AB + CD \rightarrow AD + CB\): This matches the definition of a double-replacement reaction, where two compounds exchange components.
- \(A + B \rightarrow AB\): This is a synthesis or combination reaction, where two or more substances combine to form a single product.
- \(AB \rightarrow A + B\): This is a decomposition reaction, where a single compound breaks down into two or more simpler substances.
- Conclusion
Based on the definition of a double-replacement reaction as an exchange of components between two ionic compounds, the generalized equation \(AB + CD \rightarrow AD + CB\) is the correct representation. Thus, the final answer is \(\boxed{AB + CD \rightarrow AD + CB}\).
Examples
Double-replacement reactions are fundamental in chemistry, such as the precipitation reaction used to treat hard water. For instance, when sodium carbonate (a component of some water softeners) is added to hard water containing dissolved calcium chloride, they undergo a double-replacement reaction: \[Na_2CO_3(aq) + CaCl_2(aq) \rightarrow 2NaCl(aq) + CaCO_3(s).\] The solid calcium carbonate formed is removed, effectively softening the water. Understanding this pattern helps chemists predict the products of mixing various aqueous solutions.