mixed stoichiometry

Question

One of the decomposition products of ammonium nitrate can be dinitrogen monoxide. How many milliliters of dinitrogen monoxide gas at STP are made from the decomposition on 0.75 grams of ammonium nitrate?

Answer 1

Not sure why they didn't tell you the other product is water

NH4NO3→N2O+2H2O

Convert grams NH4NO3 to moles with molar mass

0.75/80.04=0.0093703 mol NH4NO3

convert moles NH4NO3 to moles N2O with coefficients (it's 1:1)

(0.0093703 mol NH4NO3/1) × (1molN2O/1molNH4NO3)=0.0093703 mol N2O

At STP, 1 mol gas=22.4L, so

0.0093703 mol N2O × (22.4L/1mol)=0.2099 L

0.21 L N2O with sig figs