Potassium dichromate is orange in an acidic medium.it changes colour to yellow in a basic medium.

Potassium dichromate, which has the chemical formula K2Cr2O7, is indeed orange in an acidic medium. This is because in an acidic solution, the dichromate ion (Cr2O7^2-) reacts with hydrogen ions (H+) to form the chromate ion (CrO4^2-). The chromate ion is orange in color.

However, when placed in a basic medium, potassium dichromate changes color to yellow. This is due to the conversion of the dichromate ion to the chromate ion. In a basic solution, hydroxide ions (OH-) react with the dichromate ion to form the chromate ion, which is yellow in color.

In summary, potassium dichromate is orange in an acidic medium due to the presence of the dichromate ion, and it changes color to yellow in a basic medium due to the formation of the chromate ion.

The color change of potassium dichromate from orange to yellow in different environments is due to the varying oxidation states of chromium.

Potassium dichromate (K2Cr2O7) is an inorganic compound that contains the element chromium. Chromium can exist in multiple oxidation states, and these states determine the color observed.

In an acidic medium, where the concentration of hydrogen ions (H+) is high, the potassium dichromate remains in its original orange color. This is because under acidic conditions, the dichromate ion (Cr2O7^2-) maintains its oxidation state of +6. The orange color arises from the absorption of certain wavelengths of light by this ion.

However, in a basic medium, the concentration of hydroxide ions (OH-) is high, which affects the balance of oxidation states. In this scenario, potassium dichromate is reduced, leading to a change in the oxidation state of chromium. The dichromate ion (Cr2O7^2-) is converted to the chromate ion (CrO4^2-), which has an oxidation state of +4. This reduction reaction causes a shift in the absorption of light, resulting in the observed yellow color instead of orange.

So, to summarize, the orange color of potassium dichromate is observed in an acidic medium due to the presence of the dichromate ion, which has an oxidation state of +6. The yellow color is seen in a basic medium because the reduction of potassium dichromate results in the formation of the chromate ion with an oxidation state of +4.