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
|Molecular Weight/ Molar Mass||252.07 g/mol|
|Autoignition temperature||190 °C|
|Melting point||180 °C|
Ammonium Dichromate Structure – (NH4)2Cr2O7
Physical Properties of Ammonium Dichromate – (NH4)2Cr2O7
|Stability||Stable under recommended storage conditions|
|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
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 as 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.