امتزاج
في الكيمياء، الامتزاج Miscibility هي خاصية السوائل في الامتزاج بكل النسب، مشكلة محلولاً متجانساً. ويطبق المفهوم أيضا على أطوار أخرى (المواد الصلبة والغازية)، ولكن الاستخدام الأعم هو انحلالية سائل ما في آخر. الماء والإيثانول، مثلا، هما مزوجان لأنهما يمتزجان بكل النسب مع بعضهما.[1]
ويطلق اسم غير مزوج على المواد إذا لم تشكل محلولا عند بعض النسب. مثلا ثنائي إيثيل الإيثر هو مزوج إلى حد ما في الماء، ولكنهما ليسا متمازجان لأنهما لا يشكلان محولا عند جميع النسب.
By contrast, substances are said to be immiscible if the mixture does not form a solution for certain proportions. For one example, oil is not soluble in water, so these two solvents are immiscible. As another example, butanone (methyl ethyl ketone) is significantly soluble in water, but these two solvents are also immiscible because in some proportions the mixture will separate into two phases.[2]
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المركبات العضوية
In organic compounds, the weight percent of hydrocarbon chain often determines the compound's miscibility with water. For example, among the alcohols, ethanol has two carbon atoms and is miscible with water, whereas 1-butanol with four carbons is not.[3] 1-Octanol, with eight carbons, is practically insoluble in water, and its immiscibility leads it to be used as a standard for partition equilibria.[4] The straight-chain carboxylic acids up to butanoic acid (with four carbon atoms) are miscible with water, pentanoic acid (with five carbons) is partly soluble, and hexanoic acid (with six) is practically insoluble,[5] as are longer fatty acids and other lipids; the very long carbon chains of lipids cause them almost always to be immiscible with water. Analogous situations occur for other functional groups such as aldehydes and ketones.[بحاجة لمصدر]
الفلزات
Immiscible metals are unable to form alloys with each other. Typically, a mixture will be possible in the molten state, but upon freezing, the metals separate into layers. This property allows solid precipitates to be formed by rapidly freezing a molten mixture of immiscible metals. One example of immiscibility in metals is copper and cobalt, where rapid freezing to form solid precipitates has been used to create granular GMR materials.[6]
Some metals are immiscible in the liquid state. One with industrial importance is that liquid zinc and liquid silver are immiscible in liquid lead, while silver is miscible in zinc. This leads to the Parkes process, an example of liquid-liquid extraction, whereby lead containing any amount of silver is melted with zinc. The silver migrates to the zinc, which is skimmed off the top of the two-phase liquid, and the zinc is then boiled away, leaving nearly pure silver.[7]
أثر الإنتروبية
If a mixture of polymers has lower configurational entropy than the components, they are likely to be immiscible in one another even in the liquid state.[8][9]
التحديد
Miscibility of two materials is often determined optically. When the two miscible liquids are combined, the resulting liquid is clear. If the mixture is cloudy the two materials are immiscible. Care must be taken with this determination. If the indices of refraction of the two materials are similar, an immiscible mixture may be clear and give an incorrect determination that the two liquids are miscible.[10]
انظر أيضاً
المراجع
- ^ Wade, Leroy G. (2003). Organic Chemistry. Pearson Education. p. 412. ISBN 0-13-033832-X.
- ^ Stephen, H.; Stephen, T. (2013-10-22). Binary Systems: Solubilities of Inorganic and Organic Compounds, Volume 1P1 (in الإنجليزية). Elsevier. ISBN 9781483147123.
- ^ Barber, Jill; Rostron, Chris (2013-07-25). Pharmaceutical Chemistry (in الإنجليزية). OUP Oxford. ISBN 9780199655304.
- ^ Sangster, J. (1997-05-28). Octanol-Water Partition Coefficients: Fundamentals and Physical Chemistry (in الإنجليزية). John Wiley & Sons. ISBN 9780471973973.
- ^ Gilbert, John C.; Martin, Stephen F. (2010-01-19). Experimental Organic Chemistry: A Miniscale and Microscale Approach (in الإنجليزية). Cengage Learning. p. 841. ISBN 978-1439049143.
- ^ Mallinson, John C. (2001-09-27). Magneto-Resistive and Spin Valve Heads: Fundamentals and Applications (in الإنجليزية). Academic Press. p. 47. ISBN 9780080510637.
- ^ Rich, Vincent (2014-03-14). The International Lead Trade (in الإنجليزية). Woodhead Publishing. pp. 51–52. ISBN 9780857099945.
- ^ Webb, G. A. (2007). Nuclear Magnetic Resonance (in الإنجليزية). Royal Society of Chemistry. p. 328. ISBN 9780854043620.
- ^ Knoll, Wolfgang; Advincula, Rigoberto C. (2013-02-12). Functional Polymer Films, 2 Volume Set (in الإنجليزية). John Wiley & Sons. p. 690. ISBN 9783527638499.
- ^ Olabisi, Olagoke; Adewale, Kolapo (1997-03-19). Handbook of Thermoplastics (in الإنجليزية). CRC Press. p. 170. ISBN 9780824797973.