The mass of oxygen must react to form 3.80 mol of Al₂O₃ in the given reaction is 182 grams.
Mass of any substance will be calculated by using their moles as:
n = W/M, where
W = required mass
M = molar mass
Given chemical reaction is:
4Al + 3O₂ → 2Al₂O₃
From the stoichiometry of the reaction it is clear that,
2 moles of Al₂O₃ = obtained from 3 moles of O₂
3.80 moles of Al₂O₃ = obtained from 3/2×3.80=5.7 moles of O₂
Now we calculate the mass of oxygen of 5.7 moles as:
W = (5.7mol)(32g/mol) = 182.4 grams or 182g
Hence option (4) is correct.
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