Question

How many molecules (not moles) of NH3 are produced from 8.92×10−4 g of H2?
DrBob222
Convert grams H2 to moles. Then follow the steps in this example. After you know moles NH3 produced, remember that 1 mole of NH3 at STP will contain 5.022E23 molecules.
http://www.jiskha.com/science/chemistry/stoichiometry.html