Ammonium Dichromate - (NH4)2Cr2O7

What is Ammonium Dichromate?

Ammonium dichromate is a flammable inorganic compound with the chemical formula (NH4)2Cr2O7.

Ammonium dichromate is orange-red needles produced during crystallization. A toxic chemical salt is 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

Table of Contents

Ammonium Dichromate Structure – (NH4)2Cr2O7

Ammonium Dichromate 1

General Properties of Ammonium Dichromate – (NH4)2Cr2O7

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

Physical Properties of Ammonium Dichromate – (NH4)2Cr2O7

Odour Odourless
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 material.
  • It is used as an approved pesticide and used as a mordant for dyeing, used as a pigment.

Frequently Asked Questions – FAQs


What are the uses of ammonium dichromate?

Ammonium dichromate has been used as a source of pure nitrogen in the laboratory and also as a catalyst in pyrotechnics. This compound also played an important role In the early days of photography as well as in lithography. It is also used in the manufacture of alizarin, chromium alum, leather tanning, and oil purification as a mordant for dyeing pigments.


What happens when ammonium dichromate is heated?

Upon heating, ammonium dichromate decomposes to create nitrogen dioxide, water vapour (Water is gaseous in this reaction due to the relatively high reaction temperature), and solid chromium (III) oxide.


Is ammonium dichromate ionic or covalent?

The ammonium dichromate molecule can be considered an ionic compound because it features an ionic bond between the ammonium cation and the dichromate anion. However, the individual polyatomic cation and anion are held together by covalent bonds.


Is ammonia bicarbonate baking soda?

NH4HCO3, or ammonium bicarbonate, is a typical leavening agent that produces carbon dioxide without the use of an acid. It doesn’t have the alkaline flavour of baking powder or soda.


Why does baking soda smell like ammonia?

Baking soda will react like an acid, resulting in the formation of tiny amounts of sodium ammonium carbonate. When baking soda is combined with an ammonium salt and water, ammonia is produced.

Test your knowledge on ammonium dichromate!


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