Chromate vs. Dichromate

What's the Difference?

Chromate and dichromate are both chemical compounds that contain the element chromium. Chromate, with the chemical formula CrO4^2-, is a yellow-colored ion that is commonly found in various minerals. It is a stable compound and is often used as a pigment in paints and dyes. On the other hand, dichromate, with the chemical formula Cr2O7^2-, is an orange-colored ion that is derived from chromate. It is a more powerful oxidizing agent compared to chromate and is commonly used in industrial processes such as metal plating and the production of pigments. Additionally, dichromate is also used as a laboratory reagent for various chemical tests. Overall, while both chromate and dichromate contain chromium, they differ in color, stability, and their applications.


Chemical FormulaCrO42-Cr2O72-
Number of Oxygen Atoms47
SolubilitySoluble in waterSoluble in water
UsesUsed in pigments, dyes, and tanningUsed in pigments, dyes, and tanning

Further Detail


Chromate and dichromate are two inorganic compounds that contain the chromate ion. These compounds have various applications in different fields, including chemistry, industry, and even art. While they share similarities, they also possess distinct attributes that set them apart. In this article, we will explore the characteristics, properties, and uses of chromate and dichromate.

Chemical Structure

Both chromate and dichromate ions are polyatomic anions composed of oxygen and chromium atoms. The chromate ion (CrO42-) consists of one chromium atom bonded to four oxygen atoms, while the dichromate ion (Cr2O72-) contains two chromium atoms bonded to seven oxygen atoms. This structural difference gives rise to variations in their properties and reactivity.


One of the most noticeable differences between chromate and dichromate is their color. Chromate compounds are typically yellow in color, while dichromate compounds exhibit a vibrant orange-red hue. This color variation arises due to the difference in the electronic structure of the two ions. The presence of additional oxygen atoms in the dichromate ion leads to a shift in the absorption spectrum, resulting in the distinct coloration.


When it comes to solubility, chromate and dichromate ions display different behaviors. Chromate salts, such as sodium chromate (Na2CrO4), are generally more soluble in water compared to dichromate salts, such as potassium dichromate (K2Cr2O7). This solubility difference can be attributed to the increased charge density of the dichromate ion, which leads to stronger electrostatic interactions and reduced solubility.

Redox Reactions

Both chromate and dichromate ions are capable of undergoing redox reactions, but their reactivity differs. Chromate ions can act as oxidizing agents, accepting electrons to form chromium(III) compounds. On the other hand, dichromate ions are even stronger oxidizing agents, readily accepting multiple electrons to form chromium(III) or chromium(II) compounds. This difference in reactivity arises from the additional oxygen atoms present in the dichromate ion, which provide more sites for electron acceptance.


Chromate and dichromate compounds find applications in various fields due to their unique properties. Chromate compounds are commonly used as pigments in paints, dyes, and inks, thanks to their vibrant yellow color. They are also utilized in electroplating processes, corrosion inhibitors, and as catalysts in organic synthesis. Dichromate compounds, on the other hand, are widely employed as oxidizing agents in various chemical reactions, including the preparation of organic compounds, the production of dyes, and the analysis of reducing agents.

Environmental Concerns

While chromate and dichromate compounds have numerous applications, they also pose environmental concerns. Both ions are toxic and can have detrimental effects on human health and the environment. Chromate compounds, in particular, are known to be carcinogenic and can cause respiratory issues. Due to these concerns, efforts have been made to reduce the use of chromate and dichromate compounds and find alternative, less harmful substances.


In conclusion, chromate and dichromate are two inorganic compounds that share similarities but possess distinct attributes. Their chemical structures, colors, solubilities, reactivities, and applications differ, making them suitable for various purposes. However, it is important to consider the environmental concerns associated with these compounds and explore alternative options. By understanding the characteristics of chromate and dichromate, we can make informed decisions regarding their use and work towards a safer and more sustainable future.

Comparisons may contain inaccurate information about people, places, or facts. Please report any issues.