National League for Nursing (NLN) Science Practice Exam

What type of reaction is demonstrated by the equation 2NaI + Cl2 → 2NaCl + I2?

1. Decomposition reaction

2. Synthesis reaction

3. Single replacement reaction

4. Double replacement reaction

The correct answer is: Single replacement reaction

The equation 2NaI + Cl2 → 2NaCl + I2 represents a single replacement reaction. In this type of reaction, one element replaces another element in a compound. Here, chlorine (Cl2) is displacing iodine (I) from sodium iodide (NaI) to form sodium chloride (NaCl) and iodine (I2). This is characteristic of a single replacement reaction, where an element in a compound is substituted by another element, resulting in the formation of a different compound and a different standalone element. In contrast, a decomposition reaction involves a single compound breaking down into two or more simpler substances. A synthesis reaction occurs when two or more reactants combine to form a single product, while a double replacement reaction involves the exchange of components between two compounds. In this specific case, the presence of chlorine replacing iodine in sodium iodide makes it clear that a single replacement reaction is taking place.