Mass of oxygen gas produced : 14.08 g
Further explanation
Reaction
2H₂O(l)⇒2H₂(g)+O₂(g)
mol of H₂O (MW=18 g/mol) :
[tex]\tt \dfrac{20}{18}=1.1[/tex]
mol O₂ :
[tex]\tt \dfrac{1}{2}\times 1.1=0.55[/tex]
mass O₂ (theoretical) :
[tex]\tt 0.55\times 32=17.6~g[/tex]
mass O₂ (actual) :
[tex]\tt =\%yield\times theoretical\\\\=0.8\times 17.6=14.08[/tex]
