Alcohols Phenols and EthershardNUMERICAL

When detecting the presence of explosive peroxides in an aged ether sample, a chemical test is perfoAlcohols Phenols and Ethers Chemistry Question

Question

When detecting the presence of explosive peroxides in an aged ether sample, a chemical test is performed using ferrous ammonium sulfate and potassium thiocyanate. In the intensely colored blood-red coordination complex that visually confirms a positive test, what is the exact formal positive oxidation state of the central transition metal ion?

Answer: 3

💡 Solution & Explanation

The peroxides present in the ether act as oxidizing agents, oxidizing the added $Fe^{2+}$ (ferrous) ions to $Fe^{3+}$ (ferric) ions. The newly formed $Fe^{3+}$ ions immediately react with the added thiocyanate ions ($SCN^-$) to form a blood-red complex, $[Fe(SCN)_n]^{(3-n)+}$. The central iron atom is strictly in the $+3$ oxidation state.

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