Final answer:
Hydrogen bromide and hydrogen iodide are not prepared with sulfuric acid because it is an oxidizing agent that converts bromide and iodide to their elemental halogens. Instead, phosphoric acid is used as it is a weaker oxidizing agent that facilitates the formation of hydrogen halides without unwanted oxidations.
Step-by-step explanation:
The process of making hydrogen bromide or hydrogen iodide by reacting sodium bromide or sodium iodide with sulfuric acid is not typically practiced because sulfuric acid is an oxidizing agent. This means that sulfuric acid has the ability to oxidize bromide and iodide ions to their elemental forms of bromine and iodine, respectively. Instead, phosphoric acid can be used to prepare these hydrogen halides because it is a less potent oxidizing agent.
The reaction with phosphoric acid is shown as H3PO4(l) + Br−(aq) → HBr(g) + H2PO4−(aq) for hydrogen bromide. The choice of reagent is crucial here because an acid that does not oxidize the halides is needed to ensure the preparation of hydrogen halides without side reactions.