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  2. Chemical substance - Wikipedia

    en.wikipedia.org/wiki/Chemical_substance

    While the term chemical substance is a precise technical term that is synonymous with chemical for chemists, the word chemical is used in general usage to refer to both (pure) chemical substances and mixtures (often called compounds), [14] and especially when produced or purified in a laboratory or an industrial process.

  3. Chemical compound - Wikipedia

    en.wikipedia.org/wiki/Chemical_compound

    Any substance consisting of two or more different types of atoms (chemical elements) in a fixed stoichiometric proportion can be termed a chemical compound; the concept is most readily understood when considering pure chemical substances.

  4. List of purification methods in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_purification...

    The pure solid crystals are then separated from the remaining liquor by filtration or centrifugation. Recrystallization : In analytical and synthetic chemistry work, purchased reagents of doubtful purity may be recrystallised, e.g. dissolved in a very pure solvent, and then crystallized, and the crystals recovered, in order to improve and/or ...

  5. Chemistry - Wikipedia

    en.wikipedia.org/wiki/Chemistry

    Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.

  6. Chemical impurity - Wikipedia

    en.wikipedia.org/wiki/Chemical_impurity

    In chemistry and materials science, impurities are chemical substances inside a confined amount of liquid, gas, or solid. They differ from the chemical composition of the material or compound. [1] Firstly, a pure chemical should appear in at least one chemical phase and can also be characterized by its phase diagram.

  7. Separation process - Wikipedia

    en.wikipedia.org/wiki/Separation_process

    A separation process is a method that converts a mixture or a solution of chemical substances into two or more distinct product mixtures, [1] a scientific process of separating two or more substances in order to obtain purity. At least one product mixture from the separation is enriched in one or more of the source mixture's constituents.

  8. Mixture - Wikipedia

    en.wikipedia.org/wiki/Mixture

    It is an impure substance made up of 2 or more elements or compounds mechanically mixed together in any proportion. [1] A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions, suspensions or colloids. [2] [3]

  9. Law of definite proportions - Wikipedia

    en.wikipedia.org/wiki/Law_of_definite_proportions

    The law of definite proportion was given by Joseph Proust in 1797. [2]I shall conclude by deducing from these experiments the principle I have established at the commencement of this memoir, viz. that iron like many other metals is subject to the law of nature which presides at every true combination, that is to say, that it unites with two constant proportions of oxygen.