12th||NEET||JEE MAINS||D-BLOCK ELEMENTS (LECTURE VII)||POTASSIUM DICHROMATE(PREPARATION & PROPERTIES

Hello everyone Potassium dichromate which is used as a strong oxidizing agent have formula K2Cr2O7. This is an ionic compound. This is prepared from chromite ore , having formula FeO.Cr2O3, in three steps:- I) roasting of mixture of ore and sodium carbonate. Ii) treatment with concentrated sulphuric acid Iii) reaction with KCl. It is an orange colour compound which is in equilibrium with yellow colour compound at pH 4. It gives chromyl chloride test with a chloride and sulphuric acid. It reacts with hydrogen peroxide to form CrO5 or CrO(O2)2. In dichromate ion 6 Cr-O bonds are equal in length.