What is chromatography used for in chemistry?

Chromatography is a laboratory technique that is specifically designed to separate components of a mixture based on their movement rates. This process relies on the differential affinities of the components for a stationary phase and a mobile phase. In a typical chromatography setup, the mixture is dissolved in a liquid (the mobile phase), which then travels through a solid material (the stationary phase). As the mobile phase moves, different components of the mixture travel at different rates depending on their interactions with the stationary phase, thus achieving separation.

The ability of chromatography to separate substances is crucial in many applications, such as purifying chemical compounds, analyzing complex mixtures like pharmaceuticals, and identifying components in biological samples. By adjusting the conditions of the stationary and mobile phases, chemists can optimize the separation of the components based on their chemical properties.

In contrast, the other options revolve around different physical measurements or processes that do not involve the separation of mixtures. Heating a solution to induce evaporation, determining boiling points, and measuring freezing points all pertain to thermal properties of substances rather than their chemical separation.