Question

Describe how you could use IR spectroscopy to distinguish between ethyl acetate and butyric acid.The IR spectrum of butyric acid should have a broad signal between 1650 cm-1 and 1850 cm-1. An IR spectrum of ethyl acetate will not have this signal.The IR spectrum of butyric acid should have a broad signal between 2500 cm-1 and 3600 cm-1. An IR spectrum of ethyl acetate will not have this signal.The IR spectrum of ethyl acetate should have a broad signal between 2500 cm-1 and 3600 cm-1. An IR spectrum of butyric acid will not have this signal.The IR spectrum of ethyl acetate should have a broad signal between 1650 cm-1 and 1850 cm-1. An IR spectrum of butyric acid will not have this signal.

Answer 1

Butyric acid will have a broad signal between 2500 cm⁻¹ and 3600 cm⁻¹ in its IR spectrum due to carboxylic acid O-H stretch, while ethyl acetate shows a strong carbonyl stretch peak in the 1650-1750 cm⁻¹ range.

Step-by-step explanation:

To distinguish between ethyl acetate and butyric acid using IR spectroscopy, you can look for the presence of distinct absorbance patterns specific to their functional groups. Butyric acid will show a broad signal between 2500 cm⁻¹ and 3600 cm⁻¹ due to the O-H stretching vibration associated with the carboxylic acid group. This signal is typically broadened because of intermolecular hydrogen bonding. Ethyl acetate, on the other hand, will not have this broad signal as it lacks the carboxylic acid group. Instead, ethyl acetate is an ester and will exhibit a strong peak in the region of 1650-1750 cm⁻¹ due to the C=O stretching vibration of the carbonyl group in esters. IR spectroscopy is a valuable tool in organic chemistry as different functional groups display characteristic absorption frequencies, allowing chemists to readily identify which groups are present in a molecule.

Answer 2

The IR spectrum of butyric acid should have a broad signal between 2500 cm⁻¹ and 3600 cm⁻¹. An IR spectrum of ethyl acetate will not have this signal.

Step-by-step explanation:

IR spectroscopy is a widely used technique in chemical identifications. In a IR spectrum, signals depend of nature of bonds in the chemical structure of the compound.

Ethyl acetate is an esther. Its principal signal is between 16500cm⁻¹ and 1850cm⁻¹ (Carboxylic compound).

Butyric acid is a carboxylic acid. Carboxylic acids have 2 principal signals: The first is between 16500cm⁻¹ and 1850cm⁻¹ (Carboxylic compound) and the second is between 2500cm⁻¹ and 3600cm⁻¹ (Due the hydrogen bonding between O-H atoms).

Thus, right answer is:

The IR spectrum of butyric acid should have a broad signal between 2500 cm⁻¹ and 3600 cm⁻¹. An IR spectrum of ethyl acetate will not have this signal.