Need some help with stoichiometry questions

Question

Ammonium perchlorate (NH4CLO4) is the solid rocket fuel used by the U.S. Space Shuttle. It reacts with itself to produce nitrogen gas (N2), chlorine gas (Cl2), oxygen gas (O2), H2O, and a great deal of energy.

What mass of nitrogen gas is produced by the reaction of 7.8 g of ammonium perchlorate?

Round to 2 significant digits.

Answer 1

The molecular weight of ammonium perchlorate is 117.49 g/mol.

It means that 7.8 g of ammonium perchlorate contain 0.0664 mol of ammonium perchlorate.

Each mole of ammonium perchlorate contains 1 mole of nitrogen atoms, and the mass of one mole of nitrogen atoms is 14 g.

Therefore 0.0664 mol of ammonium perchlorate contain 0.0664 mol Nitrogen atoms, therefore the total mass of Nitrogen one can obtain is

0.0664 mol x 14 g N / mol = 0.93 g

It is worth noting that the product is Nitrogen gas with the formula of N₂ and molecular weight of 28 g/mol, but these facts have no effect on the calculation.