Question

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

Answer 1

The molar ratio is as you have written.

Explanation:

`(NH_4)_2Cr_2O_7(g) rarr N_2(g) + 4H_2O(l) + Cr_2O_3(s) + Delta`

This is a stoichiometrically balanced equation. It tells us explicitly that `252.1*g` of ammonium chromate decomposes under heating to give `14*g` of dinitrogen gas, `72*g` of water, and `152*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` `mol` `"ammonium dichromate"` decomposes to give `1` `mol` `"dinitrogen gas"` + etc. If you are not satisfied, voice your objections, and someone here will have another go.