What critical piece of information must be known (or given in the problem) in order to determine the molecular formula for a compound from its empirical compound?

1 Answer
anor277
Oct 6, 2016

The molecular mass of the compound is required to calculate the molecular formula from the empirical formula.

Explanation:

The #"empirical formula"# is the simplest whole number ratio defining constituent atoms in a species. The #"molecular formula"# is always a multiple of the #"empirical formula"#, and of course the multiple may be one. Without the molecular mass, we have no way of interrogating the molecular formula, even though we know that it is a multiple of the empirical formula. And thus,

#"molecular formula"# #=# #nxx{"empirical formula"}#

#n# must be determined by some means.

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