What property does a spectrophotometer measure?

A spectrophotometer is an analytical instrument that measures the intensity of light as a function of wavelength. It is commonly used to determine the concentration of solutes in a solution based on the principle of electromagnetic radiation. When light passes through a sample, some wavelengths of light are absorbed by the molecules in the solution while others are transmitted. The amount of light absorbed at specific wavelengths correlates with the concentration of the absorbing species, allowing for quantitative analysis.

This instrument operates on Beer-Lambert Law, which relates the absorption of light to the properties of the material through which the light is traveling. Each substance has a unique absorbance spectrum, making it possible to identify and quantify different compounds based on their specific light absorption characteristics.

In contrast, measuring the temperature of a solution, the concentration of solid particles, or the volume of gas produced in a reaction involves different types of instruments or methods that do not relate to light absorption and transmission, which is the fundamental function of a spectrophotometer. Therefore, the only property that a spectrophotometer measures directly is the intensity of light at different wavelengths.