Given
Mass of magnesium nitride: 3.8 g
Mass of water: 3.3 g
Mass of mgO : 3.6 g
Mg3N2 + 3 H2O --> 2 NH3+ 3 MgO
Now we know that moles=
mass of the sample/ molecular mass of the sample
Moles of Mg3N2=
given mass of Mg3N2/molecular mass of Mg3N2
Moles of Mg3N2 = 3.8/101=0.038
Moles of H2O=
given mass of H2O /molecular mass of H2O
Moles of H2O = 3.3 /18= 0.18
According to the equation since there are 3 entities of H2O we get number of moles equals 0.55.
Moles of MgO from the equation we can calculate as
Moles of MgO = 0.038 x3=0.114
Thus the mass of MgO can be calculated as no of molesx molecular mass
Mass of MgO= 0.114 x 40.33=4.59g (This is the theoretical amount present).
Actual amount present equals 3.6 g
Thus the% yield = (actual amount)/(theoretical amount) x 100
% yield= (3.6/4.59) x 100= 78.42
