What instrument is commonly used to measure the absorbance of a solution?

The spectrophotometer is the instrument specifically designed to measure the absorbance of a solution. It operates by passing light through a sample and detecting the intensity of light before and after it travels through the solution. The difference in light intensity quantifies how much light was absorbed by the sample, which is crucial for determining concentration of substances in the solution according to Beer-Lambert Law. This measurement is fundamental in various applications, including biochemistry, clinical analysis, and environmental testing.

Other instruments mentioned, like a microscope, are primarily used for visual examination of specimens, rather than quantifying absorbance. A pH meter measures the acidity or alkalinity of a solution, focusing on ion concentration rather than light absorption. The refractometer assesses how much light bends or refracts when it passes through a solution, which is useful for determining concentration but does not directly measure absorbance.