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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. 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.

  4. Mixture - Wikipedia

    en.wikipedia.org/wiki/Mixture

    [8] [9] Mixtures differ from chemical compounds in the following ways: The substances in a mixture can be separated using physical methods such as filtration, freezing, and distillation. There is little or no energy change when a mixture forms (see Enthalpy of mixing). The substances in a mixture keep their separate properties.

  5. List of purification methods in chemistry - Wikipedia

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

    Electrolysis refers to the breakdown of substances using an electric current. This removes impurities in a substance that an electric current is run through; Sublimation is the process of changing of any substance (usually on heating) from a solid to a gas (or from gas to a solid) without passing through liquid phase. In terms of purification ...

  6. Liquidus and solidus - Wikipedia

    en.wikipedia.org/wiki/Liquidus_and_solidus

    For pure elements or compounds, e.g. pure copper, pure water, etc. the liquidus and solidus are at the same temperature, and the term melting point may be used. There are also some mixtures which melt at a particular temperature, known as congruent melting. One example is eutectic mixture. In a eutectic system, there is particular mixing ratio ...

  7. Critical point (thermodynamics) - Wikipedia

    en.wikipedia.org/wiki/Critical_point...

    The figure shows the schematic P-T diagram of a pure substance (as opposed to mixtures, which have additional state variables and richer phase diagrams, discussed below). The commonly known phases solid , liquid and vapor are separated by phase boundaries, i.e. pressure–temperature combinations where two phases can coexist.

  8. 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.

  9. Directive 67/548/EEC - Wikipedia

    en.wikipedia.org/wiki/Directive_67/548/EEC

    The Directive ceased to be in force on 31 May 2015 and was repealed by Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006 (Text ...