# Question #c6029

Jan 2, 2015

You can't. You need a structural formula to identify a peroxy group.

Consider the molecular formula CH₄O₃.

This could represent either hydroxyacetic acid

or peroxyacetic acid

or methyl peroxyformate, H-C(=O)-O-OCH₃

The latter two structures contain peroxy groups, but you need more information than the molecular formula to decide which compound you have.