Ammoniumdikromat

Ammoniumdikromat is an inorganic chemical compound with the formula (NH4)2Cr2O7. It is a vibrant orange-red crystalline solid. This compound is a salt formed from the ammonium cation (NH4+) and the dichromate anion (Cr2O7^2-).

Ammoniumdikromat is known for its thermal instability. When heated, it undergoes a vigorous exothermic decomposition reaction, famously producing a "volcano" effect. This reaction releases nitrogen gas, water vapor, and chromium(III) oxide (Cr2O3), which appears as a fluffy green residue. This property has led to its use in pyrotechnics and as a laboratory demonstration of chemical reactions.

The compound is soluble in water, forming an orange solution. Like other dichromate salts, ammoniumdikromat is a strong oxidizing agent. This oxidizing power means it can react readily with reducing agents. Due to the toxicity of chromium(VI) compounds, ammoniumdikromat should be handled with care. Exposure can cause skin irritation and other health issues. Its use and disposal are subject to environmental regulations. Historically, it has found applications in photography, tanning, and as a pigment, though these uses have largely been superseded by safer alternatives.