When 2.5g of ammonium dichromate is heated, the mass of nitrogen and water vapor released is 1.0g. What is the final mass of the solid product?

Answer 1

(NH4)2Cr2O7 → Cr2O3 + N2 + 4H2O
.....2.5...................x........[1.0g]
The Law of conservation of mass tells you that you don't lose anything.
2.5 = mass Cr2O3 + 1.0
mass Cr2O3 = ?

Answer 2

Cr203=1.5 grams