# (NH_4)_2Cr_2O_7 (s) -> N2 (g) + 4H_2O (g) + Cr_2O_3 (s) + 200 kJ. What is the molar ratio?

Jul 6, 2016

${\left(N {H}_{4}\right)}_{2} C {r}_{2} {O}_{7} \left(g\right) \rightarrow {N}_{2} \left(g\right) + 4 {H}_{2} O \left(l\right) + C {r}_{2} {O}_{3} \left(s\right) + \Delta$
This is a stoichiometrically balanced equation. It tells us explicitly that $252.1 \cdot g$ of ammonium chromate decomposes under heating to give $14 \cdot g$ of dinitrogen gas, $72 \cdot g$ of water, and $152 \cdot g$ chromium(III) oxide. If you add up the product and reactant masses, you will see that they agree; and they must agree, that is mass is conserved in every chemical reaction.
So in molar terms, $1$ $m o l$ $\text{ammonium dichromate}$ decomposes to give $1$ $m o l$ $\text{dinitrogen gas}$ + etc. If you are not satisfied, voice your objections, and someone here will have another go.