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Question
Empirical formula of a compound is CH2O. If its empirical formula is equal to its vapour density, calculate the molecular formula of the compound.
Solution
Empirical formula of the compound is CH2O.
Empirical formula mass = Atomic mass of C + Atomic mass of H + Atomic mass of O
= 12 + 2 x 1 + 16 = 30.
Now as empirical formula is equal to the vapour density then;
Molecular mass = 2 x vapour density
= 2 x 30 = 60
n = Molecular mass/Empirical formula mass
= 60 / 30 = 2
Molecular formula = n x empirical formula
= 2 x (CH2O) = C2H4O2
The molecular formula of the compound is C2H4O2
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