Calculate the mass of ammonia produced when 11.2cm3 of nitrogen gas is reacted with excess hydrogen gas

Answer 1

N2 + 3H2 ==> 2NH3

When gases are used one may use cc directly as if they were mols.
11.2 cc N2 x (2 mols NH3/1 mol N2) = 11.2 x 2/1 = 22.4 cc NH3 gas produced.

Answer 2

And now convert to mass since 22.4L = 1 mole = 17g