Treatment of gold metal with brf3 and kf produces br2 and kauf4, a salt of gold. part a identify the oxidizing agent in this reaction.

Let's write the reaction first:

2 Au + 2 BrF₃ + 2 KF → 2 KAuF₄ + Br₂ 

To know which of the substances is the oxidizing agent, calculate the oxidation numbers of each element before and after the reaction. If the element's oxidation number decreases, then that is the oxidation agent. Let's calculate Br.

BrF₃: x + 3(-1) = 0; x = +3
Br₂: 0 (for any elemental form, oxidation number is 0)

The oxidation number is reduced from +3 to 0. Thus, BrF₃ is the oxidizing agent.