Ammonium dichromate is an inorganic compound with the chemical formula (NH4)2Cr2O7. It is a salt consisting of ammonium ions and dichromate ions . It is commonly used in the laboratory as an oxidizing agent and as a source of chromium . Ammonium dichromate has several uses in different fields. It is used as a source of pure nitrogen in the laboratory and as a catalyst in pyrotechnics . It is also used in sensitizing solutions used in lithography . In the early days of photography, ammonium dichromate played an important role as an alternative to potassium dichromate . It is also used as a mordant for dyeing and as a pigment .