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EMPIRICAL AND MOLECULAR FORMULAE
Empirical formula is the simplest formula which gives the ratio of the number of different atoms present in a compound. It does not give the exact number of each atom whereas the molecular formula gives the exact number of the atoms present in a molecule of a compound.
The molecular formula of a compound is a whole number multiple of its empirical formula.
Examples:
Find the empirical formula of a compound which on analysis yields the following as the reacting masses carbon= 2.0, hydrogen=0.34g, Oxygen = 2.67g. From your result find the molecular formula of the compound. If it’s relative molecular mass is 60. (C=12, H=1, O=16)
Solution:
(CH2O)X = 60
(12 + (2×1) + 16)x =60
(12+2+16)x = 60
(30)x = 60
X =Â 2
Molecular formula is, therefore (CH2O)2
=C2H4O2 or CH3COOH
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