Sodium dichromate is an inorganic compound with the formula Na2Cr2O7. Usually, the salt is handled as its dihydrate Na2Cr2O7·2H2O. Virtually all chromium ores are processed after conversion to sodium dichromate and then all compounds and materials, based on chromium are prepared from this salt. In terms of reactivity and appearance, sodium dichromate and potassium dichromate are very similar. The sodium salt is, however, around twenty times more soluble in water than the potassium salt (49 g/L at 0 °C) and its equivalent weight is also lower, which is often desirable.