Na2CrO4 on treatment with lead acetate gives a precipitate. This precipitate is dried and the solid is used as a pigment for road signs and markings. The solid is known as

The reaction is given below: 2 4 3 4 3 2 yellow Na CrO + CH COO Pb PbCrO + 2CH COONa -> 80. Potassium dichromate is used (a) in electroplating (b) as a reducing agent (c) oxidise ferrous ions into ferric ions in acidic media as an oxidising agent (d) as an insecticide The potassium dichromate acts as a powerful oxidizing agent. It oxidizes the ferrous ion 2+ Fe into the ferric ions 3+ Fe in an acidic medium. Dichromate ion takes up the electron in acidic medium and acts as an oxidizing agent. The reaction of oxidization of ferrous ion is as follows, 2+ 2- + 3+ 3+ 2 7 2 6Fe + Cr O +14H 6Fe