What is the difference between the #"molecular and empirical formulae?"#

1 Answer
anor277
Nov 27, 2016

The difference between an empirical formula mass and a molecular mass.........? See here and links.

Explanation:

The difference is a whole number multiple.

The molecular formula is always a whole number multiple of the empirical formula. Take a simple molecule such as #"ethane, " H_3C-CH_3#. The empirical formula is the simplest whole number multiple tha represents the atomic proportion of this formula, i.e. #CH_3#.

And given that #"molecular formula"# #=# #nxx"empirical formula"#, in this case #n=2#.

Typically, an analyst can give you a percentage composition of your compound; i.e. #%C, H, N#; this gives an empirical formula by standard means. And then this empirical formula is converted to a molcular formula if some way of assessing the molecular mass (i.e. mass spec., boiling point elevation) can be found.

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