In an aqueous solution the color change exhibited can be used to test for distinguishing aldehydes from ketones.

Treatment with cold sulfuric acid gives red crystals of chromic anhydride (chromium trioxide, CrO3): On heating with concentrated acid, oxygen is evolved: Potassium dichromate has few major applications, as the sodium salt is dominant industrially.

In 1852, Henry Fox Talbot discovered that exposure to ultraviolet light in the presence of potassium dichromate hardened organic colloids such as gelatin and gum arabic, making them less soluble.

Typically, after exposure, the unhardened portion was rinsed away with warm water, leaving a thin relief that either contained a pigment included during manufacture or was subsequently stained with a dye.

Chromium intensification or Photochromos uses potassium dichromate together with equal parts of concentrated hydrochloric acid diluted down to approximately 10% v/v to treat weak and thin negatives of black and white photograph roll.

After thorough washing and exposure to actinic light, the film can be redeveloped to its end-point yielding a stronger negative which is able to produce a more satisfactory print.

The development is then stopped by copious washing and the film then treated in the acid dichromate solution.

This process can be coupled with solarisation so that the end product resembles a negative and is suitable for printing in the normal way.

Cr(VI) compounds have the property of tanning animal proteins when exposed to strong light.

Once the dichromate mixture is dry, a full-size photographic positive is attached securely onto the surface of the screen, and the whole assembly exposed to strong light – times vary from 3 minutes to a half an hour in bright sunlight – hardening the exposed colloid.

Because it is non-hygroscopic, potassium dichromate is a common reagent in classical "wet tests" in analytical chemistry.

Reacting the sample with an excess of potassium dichromate, all ethanol is oxidized to acetic acid: Full reaction of converting ethanol to acetic acid: The excess dichromate is determined by titration against sodium thiosulfate.

Potassium dichromate paper can be used to test for sulfur dioxide, as it turns distinctively from orange to green.

It has only been reported as vug fillings in the nitrate deposits of the Atacama Desert of Chile and in the Bushveld igneous complex of South Africa.

[14] Aquatic organisms are especially vulnerable if exposed, and hence responsible disposal according to the local environmental regulations is advised.