Why can mixtures be separated by physical means?

Mixtures can be separated by physical means because their components retain their original properties and are not chemically combined.

In a mixture, the substances involved do not undergo any chemical changes or reactions. They simply coexist in the same space, each retaining its own individual properties. This is why we can separate them using physical methods, which are processes that do not alter the chemical nature of the substances involved.

For instance, if you have a mixture of sand and iron filings, you can use a magnet to attract the iron filings, effectively separating them from the sand. This is possible because the iron filings have a property (magnetism) that the sand does not. Similarly, if you have a mixture of salt and water, you can separate them by evaporation. The water will evaporate, leaving the salt behind. This is possible because water has a lower boiling point than salt.

There are several physical methods used to separate mixtures, including filtration, crystallisation, distillation, and chromatography. The choice of method depends on the type of mixture and the properties of its components. For example, filtration is used when one component is a solid and the other is a liquid, while distillation is used when the components are liquids with different boiling points.

In summary, the ability to separate mixtures by physical means is a result of the fact that the components of a mixture retain their original properties and are not chemically combined. This allows us to exploit differences in these properties to separate the components.