Chemistry - Gravimetric analysis - activity 5
Gravimetric analysis - activity 5
Analysis of a compound shows it to contain only carbon and oxygen. A 10 g
sample of the compound contains 2.73 g of carbon. Determine the empirical
formula of the compound.
The experimental link between the empirical formula and molecular formula
of a compound is the relative molecular mass _M_r of the compound.
There is a simple mathematical relationship, namely
EFM (empirical formula mass) is determined by adding up the relative
atomic masses according to the empirical formula.
Relative molecular mass (_M_r) is deduced from the molar mass, which is
determined from experimental data, generally using a modified form of the
general gas equation,_ pV = nRT._
Molar mass (M) is readily incorporated into the general gas equation via
_n = m / M._
So in order to determine the molar mass, and hence relative molecular
mass, of a substance the experimental data available must include: mass of
the sample, temperature, pressure and volume.
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