Which of the following is an oxidizing chemical?

• A. Potassium dichromate
• B. Sodium hydride
• C. Magnesium
• D. Sodium

Answer: (A)

An oxidizing chemical is a substance that accepts electrons in a redox reaction and is reduced as it causes another substance to be oxidized. Potassium dichromate is a classic strong oxidizer, especially in acidic solutions, because chromium is in a high oxidation state (+6) and is reduced to Cr3+ as it pulls electrons from the substance being oxidized. This ability to accept electrons and drive oxidation of other reactants makes it a powerful oxidizing agent, commonly used in tests and in oxidations of alcohols under acidic conditions. Sodium hydride acts as a hydride donor and a strong base, so it behaves as a reducing agent rather than an oxidizer. Magnesium and sodium are reactive metals that tend to be oxidized themselves, also functioning as reducing agents rather than oxidizers.