Ammonia is produced by the reaction of hydrogen and nitrogen according to this balanced equation:?

I'm guessing that they provided a number on the grams of nitrogen because this reaction occurred in an excess of hydrogen. If there wasn't any hydrogen present, then the reaction wouldn't take place, obviously. Since we are given the amount of limiting reactant, we can simply find the number of moles of the limiting reactant ( 13.4/28.02=.478mol N2). Then, we use mole ratios to go from reactant to product. (2 mol NH3/1 mol N2 =.9568mol NH3). This is the moles of ammonia produced. Then, convert this into grams: (.9568mol NH3 * (17.02g/mol))=16.29g NH3