Why can’t impurities be completely removed in chemistry?

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The second law of thermodynamics (the principle of entropy increase) tells us that for an isolated system, it always evolves in the direction of greater disorder (a state of high entropy). ☆A completely pure substance is difficult to maintain; the concept of a pure substance exists only on a chemical level, and no completely pure substances can be found in the macroscopic world. The entropy of a perfectly pure substance must be extremely low; without any external intervention, it will spontaneously move toward a state of higher entropy and become impure. Suppose, through some means, you obtain a bottle of completely pure substance; you treat it as a precious treasure, seal it carefully, and look forward to media professionals and scientists from around the world coming in large numbers to visit and study it. But unfortunately, the container itself is also a type of material. When the substances inside the container are in direct contact with the inner walls of the container, substance exchange occurs; the molecules or atoms of the container material can enter the pure substance, thereby introducing impurities and making it impure. It is these ‘damned’ atoms and molecules that are constantly in random thermal motion, always trying to interact with other substances and destroying any illusion that they can remain pure forever. Furthermore, your “pure substance” itself will also undergo a “self-revolution,” experiencing chemical changes and transforming into something belonging to another category. These substances may undergo decomposition on their own, or even self-polymerize to form other substances, thus becoming impurities. Just as you should never expect a dirty table to clean itself automatically, you shouldn’t expect impure substances to become pure on their own. The price of becoming organized is the need to expend energy. ☆Purification is a tough task: the higher the purity requirement, the more difficult it becomes. Removing impurities means getting rid of the unwanted components in a substance, and this process reduces the entropy of that substance, making it somewhat more \"ordered\". This requires a “cost,” meaning energy must be supplied to this system. All purification processes, that is, processes for removing impurities, require energy! What’s even more disheartening is that the higher the purity required, the greater the technical difficulty of purification, and the energy consumed increases exponentially. Chemists developed a set of essential methods for purification quite early on: filtration, extraction, evaporation and concentration, distillation, electrolysis, crystallization, reverse osmosis, ion exchange, chromatography... These methods are like the essential tools of a chemist, allowing them to make the contents in their flasks completely pure. Whether they are physical methods or chemical methods, without exception, all of them require the consumption of energy and resources! However, these purification methods often have their limitations. For example, distillation can be used to remove impurities from liquids, but this method also has its limits. When it comes to purifying alcohol – a mixture of ethanol and water – distillation alone becomes ineffective once the ethanol concentration reaches 95.63%, as ethanol and water form an azeotrope at that point, preventing further purification. To achieve a purity of 99%, other methods must be employed. At the same time, distillation is only effective for liquid-liquid separation (removing liquid impurities from liquids); trying to use distillation to separate diamonds from sand is nothing but delusion. Different tools are needed for different parts of a crab, and sometimes various tools have to be used together. Similarly, different purification methods are required to separate mixtures in various states, and sometimes multiple purification methods must be used to achieve the desired level of purity. It seems that removing impurities is indeed a task with high technical difficulty, but that’s only natural – to be able to eat crabs, such necessary efforts are required.