Core
Quantitative Chemistry: Formula
Slide 14 of 37
Determination of
Empirical formula from elemental analysis II
b) From mass composition of a sample
of compound:
Elemental
analysis of 3.51 g of compound X is found to contain only 3.00 g of carbon
and 0.51 g of H. What is the empirical formula?
The whole number ratio comes out to 2.03 and not exactly 2 for
H because of experimental errors. However, when corrected to 2 sig figs as
required, it does round off to 2.
Empirical formula is CH2. Molecular formula: CxH2x. Could be CH2 itself (but no such compound exists!), or C2H4 or C3H6 or C4H8 etc.