Summary
Highlights
Separation techniques are used only for mixtures, where pure substances have been physically combined and are physically separated. They do not work for elements or compounds, which require nuclear or chemical changes, respectively. The principle is to exploit physical differences between components to separate them.
Filtration primarily exploits particle size. Smaller particles (filtrate) pass through a filter, while larger particles remain behind. An example given is coffee, where the liquid coffee is the filtrate.
Centrifugation exploits density by rapidly spinning a mixture, causing components to separate into layers based on density. Blood separation is a common example. Decanting is the process of pouring off one layer once it has separated, either through centrifugation or due to insolubility, such as separating oil and vinegar or sediment from wine.
These techniques exploit differences in boiling points. Evaporation involves heating a mixture until one component boils off, leaving the other behind (e.g., salt from seawater). Distillation is similar but involves collecting and condensing the evaporated component back into a liquid, making it a valuable technique in industries like alcohol production and petroleum refining.
Chromatography encompasses a wide range of techniques, all based on the principle of separating substances based on their differential attraction to a stationary phase and a mobile phase. A simple example is paper chromatography. Substances that are more attracted to the stationary phase move slower, while those more attracted to the mobile phase move faster, allowing for their separation.