Final answer:
In order of increasing strength, the oxidizing agents Br₂(aq), Fe₃⁺(aq), and Cr₂O₇²⁻(aq) are arranged as Br₂(aq) < Fe₃⁺(aq) < Cr₂O₇²⁻(aq), with dichromate ions being the strongest oxidizing agent of the three.
Step-by-step explanation:
To arrange the following oxidizing agents Br₂(aq), Fe₃⁺(aq), and Cr₂O₇²⁻(aq) in order of increasing strength, we need to look at their tendencies to gain electrons (which constitutes their oxidizing capabilities) under standard state conditions. Oxidizing strength increases with the substance's ability to attract and gain electrons, which can be inferred from standard reduction potentials.
Without the specific standard reduction potentials for these half-reactions, a general trend among the species can be considered. Dichromate ions (Cr₂O₇²⁻) typically have strong oxidizing capabilities, especially in acidic solution where the chromium is in a high oxidation state (+6). Given that in a redox reaction, it gains electrons to reduce to Cr³⁺, it is known to be a powerful oxidizer. On the other hand, molecular bromine (Br₂) and iron (III) ions (Fe₃⁺) are generally weaker oxidizers compared to Cr₂O₇²⁻, although Fe₃⁺ is a stronger oxidizing agent than Fe²⁺.
Considering these factors and the principles given in the standard activity series and trends in oxidizing strength, the order of increasing strength of the given oxidizing agents is as follows: Br₂(aq) < Fe₃⁺(aq) < Cr₂O₇²⁻(aq). This means that under standard state conditions, dichromate ions are the strongest oxidizing agent among the three.