Convert the mass of one substance (substance A) to the
corresponding number of moles using its molar mass.
From the balanced chemical equation, obtain the number of moles
of another substance (B) from the number of moles of substance A
using the appropriate mole ratio (the ratio of their
coefficients).
Convert the number of moles of substance B to mass using its
molar mass. It is important to remember that some species are in
excess by virtue of the reaction conditions. For example, if a
substance reacts with the oxygen in air, then oxygen is in obvious
(but unstated) excess.