Which of the following methods is commonly used to measure the absorption spectrum of a substance?

• A. Using a pH meter to monitor changes in acidity
• B. Using a voltmeter to detect changes in electrical potential
• C. Using a calorimeter to measure the heat released during absorption
• D. Using a spectrophotometer to record the intensity of light absorbed at different wavelengths

Answer: (D)

Verified step by step guidance

1. Understand that the absorption spectrum of a substance shows how much light is absorbed at different wavelengths, which helps identify the substance or analyze its concentration.
2. Recognize that measuring absorption involves detecting how much light passes through a sample versus how much is absorbed, which requires an instrument sensitive to light intensity at various wavelengths.
3. Know that a spectrophotometer is designed to shine light of different wavelengths through a sample and measure the intensity of transmitted light, allowing calculation of absorbance at each wavelength.
4. Recall that other instruments like pH meters, voltmeters, and calorimeters measure different properties (acidity, electrical potential, heat) and are not suitable for directly measuring light absorption.
5. Conclude that the common and appropriate method to measure the absorption spectrum is using a spectrophotometer to record the intensity of light absorbed at different wavelengths.