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.

See here for some examples.

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