When analyzing an absorbance spectrum, which approach is most appropriate for identifying compounds present in a mixture?

• A. Use the total area under the absorbance curve without considering peak locations.
• B. Compare the wavelengths of 1-2 key absorbance peaks to known reference spectra.
• C. Ignore peak positions and focus solely on the baseline of the spectrum.
• D. Only consider the intensity of the highest absorbance peak.

Answer: (B)

Verified step by step guidance

1. Understand the problem: The question is asking about the most appropriate approach for identifying compounds in a mixture using an absorbance spectrum. Absorbance spectra are used in analytical chemistry to identify and quantify compounds based on their interaction with light at specific wavelengths.
2. Step 1: Recall the principle of absorbance spectroscopy. Each compound has a unique absorbance spectrum, which is characterized by specific wavelengths where it absorbs light. These wavelengths correspond to electronic transitions in the molecule and are often referred to as 'key absorbance peaks.'
3. Step 2: Evaluate the options provided. The first option suggests using the total area under the absorbance curve, but this does not provide specific information about the identity of the compound, as it does not consider the unique wavelengths of absorbance. The second option suggests comparing the wavelengths of 1-2 key absorbance peaks to known reference spectra, which is a standard and effective method for identifying compounds. The third option suggests ignoring peak positions and focusing on the baseline, which is not scientifically valid for identification. The fourth option suggests only considering the intensity of the highest absorbance peak, but this alone does not provide enough information for identification.
4. Step 3: Focus on the correct approach. Comparing the wavelengths of 1-2 key absorbance peaks to known reference spectra is the most appropriate method because it leverages the unique spectral fingerprint of each compound. This method allows for accurate identification by matching the observed peaks to those in a database or reference material.
5. Step 4: Conclude that the correct answer is to compare the wavelengths of 1-2 key absorbance peaks to known reference spectra, as this method is based on the fundamental principles of absorbance spectroscopy and provides reliable identification of compounds in a mixture.