Which expression represents a single replacement reaction?

Which expression represents a single replacement reaction?

• A. AB + C --> AC + B
• B. AB + CD --> AD + CB
• C. AB --> A + B
• D. A + B --> AB

Answer: (A)

Single replacement reactions occur when an element displaces another element in a compound, producing a new compound and a free element. In AB + C → AC + B, the single element C comes in and replaces B in AB to form the new compound AC, while B is released as a free element. This exact pattern—an element taking the place of another in a compound to yield a new compound plus a standalone element—defines a single replacement. The other patterns represent different reaction types: AB + CD → AD + CB is a double replacement, where partners swap between two compounds; AB → A + B is decomposition, where a compound breaks into simpler substances; A + B → AB is synthesis, where two elements join to form a compound.

Single replacement reactions occur when an element displaces another element in a compound, producing a new compound and a free element. In AB + C → AC + B, the single element C comes in and replaces B in AB to form the new compound AC, while B is released as a free element. This exact pattern—an element taking the place of another in a compound to yield a new compound plus a standalone element—defines a single replacement.

The other patterns represent different reaction types: AB + CD → AD + CB is a double replacement, where partners swap between two compounds; AB → A + B is decomposition, where a compound breaks into simpler substances; A + B → AB is synthesis, where two elements join to form a compound.