Final answer:
The spectra correspond with carboxylic acid due to specific IR absorption peaks at 1716 cm-1 for the C=O bond and a broad band around 3400 cm-1 for the O-H bond, characteristic of the carboxylic acid functional group.
Step-by-step explanation:
The spectra in question belong to the carboxylic acid due to the presence of characteristic absorption peaks that are indicative of this functional group. Carboxylic acids contain both a carbonyl group (C=O) and a hydroxyl group (-OH) on the same carbon atom, creating a -C-OH group. In an infrared (IR) spectrum, the carboxyl group gives rise to two significant absorption peaks. One is a sharp and strong peak in the 1650-1750 cm-1 region, with carboxylic acids typically absorbing on the shorter wavelength end (1700-1750 cm-1), which identifies the presence of the C=O bond. This peak would be seen at approximately 1716 cm-1.
Moreover, carboxylic acids exhibit a low, broad absorbance band due to the O-H bond stretching, which appears displaced to the right side of the spectrum and overlaps with the C-H region. This broad band is centered around 3400 cm-1, resulting from hydrogen bonding between the carboxylic acid molecules. In addition to these strong infrared spectroscopy signals, the stratification of the overlapping p-orbitals of oxygen and carbon in the carboxyl group diminishes the electrophilic character of the carbon, which is characteristic of the carboxylic acid group's resonance stability.
Differentiating between carboxylic acids and esters, which both display the carbonyl peak, involves considering the second oxygen atom in the group. In carboxylic acids, this oxygen is bonded to a hydrogen atom, while in esters, it is bonded to another carbon atom. Lastly, the physical properties and reactivity of carboxylic acids can be attributed to their polar nature due to the three polar bonds (C=O, C-O, and O-H) that make up the carboxylic acid group.