International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

In the reaction 2HBr + Cl₂ → 2HCl + Br₂, which element is displaced?

1. Chlorine

2. Iodine

3. Bromine

4. Sodium

The correct answer is: Bromine

In the reaction given, chlorine (Cl₂) reacts with hydrogen bromide (HBr) to produce hydrogen chloride (HCl) and bromine (Br₂). This process involves a displacement reaction, where one element in a compound is replaced by another element. In this case, chlorine displaces bromine from hydrogen bromide. The presence of chlorine in the reactants leads to the formation of hydrogen chloride, while bromine is released as a separate product. Thus, bromine is the element that is displaced from its compound. Understanding the reactivity of halogens is crucial here. Chlorine is more reactive than bromine, which allows it to effectively replace bromine in the reaction. This is an essential concept in halogen chemistry, highlighting the order of reactivity among the halogens, where chlorine is able to displace bromine due to its higher electronegativity and stronger oxidizing properties.