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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.
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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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