The infrared spectrograph of a typical carboxlic acid has characteristics in common with the spectrographs of both alcohols and aldehydes & ketones. The IR spectrum of a carboxylic acid shows a broad region of overlap between the O-H and C-H stretching frequencies from 2500 to 3500 cm-1. The carbonyl group gives a strong absorption at 1700 cm-1. In HNMR, the acidic proton is very strongly deshielded, appearing 10 to 12 ppm downfield (identifiable by addition of D2O).