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# Empirical and Molecular Formulae watch

A molecule has an empirical formula of C3H7O, and a relative molecular mass of 118.
Deduce the molecular formula of the molecule.
2. Empirical formula is the simplified version of an compound's chemical formula, meaning that the ratios of the different elements in the compound are simplified to 31 (C : H : O). Given the RMM of the real compound, using the ratio you need to work out what the chemical formula of the real compound.

So, firstly, find out the RMM of the empirical compound: [(12*3)+(1*7)+(16*1)] = 36+7+16= 59 = RMM of C3H7O.
To get the mass from 59 to 118, you multiply 59 by 2, meaning that essentially the real compound is 2 times the simplified empirical formula, so = 2*(C3H7O) = C6H14O2.

I hope this makes sense. Sorry if it doesn't
3. I agree with above ^^ You find the empirical formula and divide it by the molar mass to get an integer number.
4. (Original post by marniedavies03)
Empirical formula is the simplified version of an compound's chemical formula, meaning that the ratios of the different elements in the compound are simplified to 31 (C : H : O). Given the RMM of the real compound, using the ratio you need to work out what the chemical formula of the real compound.

So, firstly, find out the RMM of the empirical compound: [(12*3)+(1*7)+(16*1)] = 36+7+16= 59 = RMM of C3H7O.
To get the mass from 59 to 118, you multiply 59 by 2, meaning that essentially the real compound is 2 times the simplified empirical formula, so = 2*(C3H7O) = C6H14O2.

I hope this makes sense. Sorry if it doesn't
Ah yes I think I've understood it now. Thank you for your help.

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