World Library  
Flag as Inappropriate
Email this Article




This article is about states of matter. For other meanings of heterogeneity, homogeneity, and related words, see Homogeneity (disambiguation) and Heterogeneity (disambiguation).

Homogeneity and Heterogeneity are concepts relating to the uniformity in a substance. A material that is homogeneous is uniform in composition or character; one that is heterogeneous is distinctly nonuniform in one of these qualities.[1][2][3]

The concepts are the same to every level of complexity, from atoms to populations of animals or people, and galaxies. Hence, an element may be homogeneous on a larger scale, compared to being heterogeneous on a smaller scale. This is known as an effective medium approach, or effective medium approximations.[4][5]


Heterogeneity is the state of being heterogeneous. It is the nature of opposition, or contrariety of qualities. It is diverse in kind or nature; composed of diverse parts, or resulting from differing causes. In general, a heterogeneous entity is composed of dissimilar parts, hence the constituents are of a different kind. The parts (or constituents) are connected, and of a conglomerate mass, and viewed in respect to the parts of which it is made up.[2][6]

Various disciplines understand heterogeneity, or being heterogeneous, in different ways. For example:

  • In physics, it is understood as having more than one phase (solid, liquid, gas) present in a system or process.
  • In chemistry, a heterogeneous material consists of either or both of a) multiple states of matter or b) hydrophilic and hydrophobic substances in one mixture; an example of the latter would be a mixture of water, octane, and silicone grease.
  • With information technology (see:Heterogeneous computing) it means a network comprising different types of computers, potentially with vastly differing memory sizes, processing power and even basic underlying architecture. Alternatively, a data resource with multiple types of formats.. A recent publication entitled "Heterogeneity in Mobile Cloud Computing: Taxonomy and Open Challenges"[7] is a beneficial and thought-provoking article for interested readers.
  • In sociology it may refer to a society or group that includes individuals of differing ethnicities, cultural backgrounds, sexes, or ages.
  • Rocks (geology) are inherently heterogeneous, usually occurring at the micro-scale and mini-scale.[4]
  • In medicine and genetics, a genetic or allelic heterogeneous condition is one where the same disease or condition can be caused, or contributed to, by several factors. In the case of genetics, varying different genes or alleles.
  • In cancer research, cancer cell heterogeneity is thought to be one of the underlying reasons that make treatment of cancer difficult.[8]


Homogeneity is the state of being homogeneous. Pertaining to the sciences, it is a substance where all the constituents are of the same nature; consisting of similar parts, or of elements of the like nature. For example, homogeneous particles, homogeneous elements, homogeneous principles, or homogeneous bodies; or (algebra) possessing the same number of factors of a given kind as with a homogeneous polynomial.[3]


A heterogeneous mixture is a mixture of two or more compounds. Examples are: mixtures of sand and water or sand and iron filings, a conglomerate rock, water and oil, a salad, trail mix, and concrete (not cement).[9] During the sampling of heterogeneous mixtures of particles, the variance of the sampling error is generally non-zero. Gy's sampling theory [10] quantitatively defines the heterogeneity of a particle as:

h_i = \frac{(c_i - c_\text{batch})m_i}{c_\text{batch} m_\text{aver}} .
h_i, the heterogeneity of the ith particle of the population
c_i, the mass concentration of the property of interest in the ith particle of the population
c_\text{batch},the mass concentration of the property of interest in the population
m_i, the mass of the ith particle in the population
m_\text{aver}, the average mass of a particle in the population

Homogenization is the process of causing a heterogeneous mixture to become homogeneous, as is done with the making of homogenized milk.

Homogeneous and heterogeneous reactions

Homogeneous reactions are chemical reactions in which the reactants are in the same phase, while heterogeneous reactions have reactants in two or more phases. Reactions that take place on the surface of a catalyst of a different phase are also heterogeneous. A reaction between two gases, two liquids or two solids is homogeneous. A reaction between a gas and a liquid, a gas and a solid or a liquid and a solid is heterogeneous.

A mixture can be determined to be homogeneous when everything is settled and equal, and the liquid, gas, object is one color or the same form. Various models have been proposed to model the concentrations in different phases. The phenomena to be considered are mass rates and reaction rates.

See also


External links

  • The following cited pages in this book cover the meaning of "homogeneity" across disciplines .eu:Homogeneo eta heterogeneo
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Hawaii eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.