Final answer:
The optimum wavelength for measuring absorbance typically lies in the visible or ultraviolet regions, depending on the substance's properties. Amax, the wavelength at maximal light absorbance, is used to determine concentrations in solutions.
Step-by-step explanation:
The optimum wavelength for measuring absorbance depends on the specific application and the substance being studied. For general purposes in organic and biological chemistry, the visible spectrum is often used, particularly when dealing with colored solutions. The ultraviolet (UV) region is also frequently utilized, especially for substances that naturally absorb in this range, such as many organic compounds. X-rays are not usually used for absorption spectroscopy in these fields. Infrared can be used for different types of analyses, for example in IR spectroscopy to look at molecular vibrations.
A key concept in this area is Amax, which stands for the wavelength at maximal light absorbance. This concept is part of UV-Vis spectroscopy and is important because the absorbance at Amax enables scientists to determine the concentration of a substance in a solution using the Beer-Lambert law. Therefore, the optimal wavelength for measuring absorbance is usually the one at which Amax occurs for the substance under examination.