When 64 g of sulfur were burned in oxygen, 120 g of sulfur (IV) oxide were obtained.

When 64 g of sulfur were burned in oxygen, 120 g of sulfur (IV) oxide were obtained. Calculate the mass fraction of the theoretically possible product yield.

Given:
m (S) = 64 g
m (SO2) = 120 g
Find:
W (practice) =?
Solution:
1) Let’s compose the equation of a chemical reaction.
S + O2 = SO2
2) Find the theoretical mass of sulfur oxide. We know the mass of sulfur, and let the mass of sulfur oxide be x g.
M (S) = 32 g / mol;
M (SO2) = 32 + 32 = 64 g / mol.
64 g: 32 g / mol = x: 64 g / mol
x = (64 x 64): 32 = 128 g
3) 128 g – 100% (since the theoretical yield is always 100%)
120 g – x%
x = (120 g x 100%): 128 g = 93.75% – practical yield.
Answer: W (practical) = 93.75%