Ammonium Dichromate - (NH4)2Cr2O7

What is Ammonium Dichromate?

Ammonium dichromate is a flammable inorganic compound with the chemical formula (NH4)2Cr2O7. It is orange-red needles produced during crystallization. A toxic chemical salt used to sensitize organic emulsions such ad gelatin to the hardening effect of actinic light. It is more sensitive to light.

IUPAC name – diammonium oxido-(oxido-dioxo-chromio)oxy-dioxo-chromium

H8Cr2N2O7

Ammonium Dichromate

Density

2.12 g/cm³

Molecular Weight/ Molar Mass

252.07 g/mol

Autoignition temperature

190 °C

Melting point

180 °C

Chemical Formula

(NH4)2Cr2O7

Ammonium Dichromate Structure – (NH4)2Cr2O7

Ammonium Dichromate

Physical Properties of Ammonium Dichromate – (NH4)2Cr2O7

Odour

Odorless

Appearance

Orange-red crystals

Stability

Stable under recommended storage conditions

Specific Gravity

2.1500

Solubility

Insoluble in acetone; soluble in alcohol

Chemical Properties of Ammonium Dichromate – (NH4)2Cr2O7

  • On heating Ammonium dichromate undergoes decomposition resulting in the formation of chromium(III) oxide and nitrogen gas.
  • (NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + 4H2O(g)

Uses of Ammonium Dichromate – (NH4)2Cr2O7

  • Ammonium dichromate is used in sensitizing solutions used in lithography.
  • Used in pyrotechnics, lithography and photoengraving. It is also used as a magnetic recording materials.
  • It is used as an approved pesticide and used as a mordant for dyeing, used as a pigment.

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