Difference Between Potassium Chromate and Potassium Dichromate

The key difference between potassium chromate and potassium dichromate is that potassium chromate appears in yellow colour, whereas potassium dichromate appears in orange colour.

Potassium chromate and potassium dichromate are closely related inorganic compounds having similar chemical structures. The dichromate ion in potassium dichromate is made from the combination of two chromate ions.

CONTENTS

1. Overview and Key Difference
2. What is Potassium Chromate 
3. What is Potassium Dichromate
4. Similarities Between Potassium Chromate and Potassium Dichromate
5. Side by Side Comparison – Potassium Chromate vs Potassium Dichromate in Tabular Form
6. Summary

What is Potassium Chromate?

Potassium chromate is an inorganic compound having the chemical formula K2CrO4. It appears in yellow colour and exists in a solid-state at room temperature. It is the potassium salt of chromate anion. This is a common chemical in the laboratory.

There are two crystalline forms of potassium chromate as orthorhombic structure and tetrahedral structure. Among them, the orthorhombic beta structure is the most common form, which can convert into alpha form at high temperatures.

We can easily produce potassium chromate by treating potassium dichromate with potassium hydroxide. Another method of production is the fusion of potassium hydroxide with chromium oxide.

Naturally, potassium chromate occurs in the mineral form ‘tarapacaite’. This mineral occurs as a rare substance on Earth.

Potassium chromate is considered a carcinogenic substance. This is common with most of the known chromium compounds, where chromium is in a +6 oxidation state. Moreover, this compound is corrosive, and it can cause damage or blindness in the eyes if contact occurs.

What is Potassium Dichromate?

Potassium dichromate is an inorganic compound having the chemical formula K₂Cr₂O₇. It has a bright, red-orange appearance. Furthermore, potassium dichromate is an oxidizing agent. Therefore, there are many applications of this compound. However, similar to many other chromium compounds, potassium dichromate is acutely harmful to our health.

Concerning the production of potassium dichromate, there are two ways to produce this substance. One method is via the reaction between potassium chloride and sodium dichromate. The second method is by roasting the chromate ore with potassium hydroxide.

Moreover, potassium dichromate readily dissolves in water, and upon dissolution, it undergoes ionization. When considering the applications, it is used as a precursor for potassium chrome alum (a chemical used in the leather industry). In addition, it is also used for cleaning purposes, in constructions, in photography, etc.

What are the Similarities Between Potassium Chromate and Potassium Dichromate?

• Potassium chromate and potassium dichromate are ionic compounds.
• Both are salts of potassium.
• These compounds contain a chromate chemical moiety.
• Both substances are mainly important for qualitative and quantitative analysis of samples through redox reactions or titrations.

What is the Difference Between Potassium Chromate and Potassium Dichromate?

Potassium chromate is an inorganic compound having the chemical formula K2CrO4, while Potassium dichromate is an inorganic compound having the chemical formula K₂Cr₂O₇. The dichromate ion in potassium dichromate is made from the combination of two chromate ions. The key difference between potassium chromate and potassium dichromate is that potassium chromate appears in yellow colour whereas potassium dichromate appears in orange colour. Furthermore, potassium chromate is created by treating potassium dichromate with potassium hydroxide while potassium dichromate is created via the reaction between potassium chloride and sodium dichromate. So, this is another difference between potassium chromate and potassium dichromate.

Moreover, potassium chromate is used for laboratory works, as an oxidizing agent, in qualitative inorganic analysis, as an indicator in precipitation titrations, etc. whereas potassium dichromate is used as a precursor for potassium chrome alum (a chemical used in the leather industry), for cleaning purposes, in constructions, in photography, etc.

Below is a summary of the difference between potassium chromate and potassium dichromate in tabular form.

Summary – Potassium Chromate vs Potassium Dichromate

Potassium chromate and potassium dichromate are closely related inorganic compounds having similar chemical structures. The key difference between potassium chromate and potassium dichromate is that potassium chromate appears in yellow colour whereas potassium dichromate appears in orange colour.

Reference:

1. “Potassium Chromate.” Wikipedia, Wikimedia Foundation, 29 Mar. 2021, Available here.

Image Courtesy:

1. “Potassium-chromate-sample” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia
2. “Potassium-dichromate-sample” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia