Understanding pure substances is essential in chemistry. For example, diamonds are one type of a pure substance because they consist only of carbon atoms. On the other hand, amber is not pure because it contains plant resins with different compounds. In the real world outside the laboratory, it is difficult to isolate pure materials. Even diamonds have impurities such as nitrogen or boron when they are mined in nature.
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The two main types of pure substances are compounds and elements. They consist of a single type of particle or compound.
Two Main Types of Pure Substances
Elements and compounds are the two types of pure substances. Examples of common elements include carbon, nitrogen and hydrogen. They consist of one type of atom and cannot break down into something else. Every pure carbon substance, for example, has the same particles in it.
Compounds such as water, salt and sugar are also pure substances. Although they are a combination of different elements, these substances still qualify because they have a consistent composition and contain only one type of compound. They also have a fixed number of elements. For instance, a cup of distilled, sterile water is a pure substance because the only compound in it is H2O.
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Types of Matter That Are Pure Substances
Matter that has a consistent and constant composition qualifies as a pure substance. One example is common table salt because it only has one type of compound in it, which is NaCl. It does not matter if you look at a pinch or a cup of salt since the only thing inside is the NaCl compounds. You will not find other compounds in pure table salt. Similarly, sugar is a pure material that only has compounds of C12H22O11.
Problems Isolating Pure Substances
It is usually hard to isolate pure substances outside the laboratory. For example, the element sodium (Na) reacts violently with water and does not exist on its own in nature, but it is easy to find it in a compound like salt (NaCl) or sodium hydroxide (NaOH). The element potassium (K) is highly reactive, which makes isolating it a challenge.
Impurities are another problem that complicates finding pure matter. Gold (Au) often has other elements such as silver or copper in it that require refining or melting the metal to remove them. A diamond is another example of a pure substance that has issues with impurities that affect its value. Nitrogen can make a diamond look yellow, and this flaw can dramatically lower the price.