Chemical change

Chemical change

--112.198.81.178 (talk) 09:44, 14 November 2011 (UTC)bla da

Chemical changes occur when objects or substances are changed or altered. In a chemical change, particles of the original materials collide with one another. Some exothermic reactions may be hot enough to cause certain chemicals to also undergo a change in state. For example, in the case of aqueous solutions, bubbles may not necessarily be newly produced gas but instead water vapor, so, chemical change is nothing but a change which is usually irreversible.

When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated. An example of a chemical change is the reaction between sodium hydroxide and hydrogen chloride to produce sodium chloride, or common salt. This reaction is so exothermic, meaning it releases heat in the form of energy, that even flames are generated. This is an example of a chemical change because the end product is molecularly different from the starting molecules.[1]

Chemical changes are happening all the time. There are several different types of chemical change, including: synthesis, decomposition, single displacement, double displacement, neutralization, precipitation, combustion and redox.

Examples of chemical changes:

Evidence of a chemical change:

The following can indicate that a chemical change took place, although this evidence is not conclusive:

  • Change of odor.
  • Change of color (for example, silver to reddish-brown when iron rusts).
  • Change in temperature or energy, such as the production (exothermic) or loss (endothermic) of heat.
  • Change of form (for example, burning paper).
  • Light, heat, or sound is given off.
  • Formation of gases, often appearing as bubbles.
  • Formation of precipitate (insoluble particles).
  • The decomposition of organic matter (for example, rotting food).

A chemical change is a change in which one or more substances are converted into different substances.
A chemical change can have a huge impact on a physical change. Chemical changes are permanent.
A chemical change changes the identity or properties of a substance and cannot easily be reversed.

References

  1. ^ Carpi, Anthony, Ph.D. “Chemical Reactions.” Vision Learning. Vision Learning Inc. , 2009. Web. 6 Oct. 2009.

Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • chemical change — noun (chemistry) any process determined by the atomic and molecular composition and structure of the substances involved • Syn: ↑chemical process, ↑chemical action • Topics: ↑chemistry, ↑chemical science • Hypernyms: ↑ …   Useful english dictionary

  • chemical change — noun any process in which reactants are changed into products by the breaking or creation of chemical bonds …   Wiktionary

  • chemical change —    Rearrangement of the atoms, ions, or radicals of one or more substances, resulting in the formation of new substance, often having entirely different properties. Also known as a chemical reaction …   Forensic science glossary

  • chemical change — /kɛmɪkəl ˈtʃeɪndʒ/ (say kemikuhl chaynj) noun a change in which one or more substances are converted into other substances …  

  • Chemical potential — Chemical potential, symbolized by μ, is a measure first described by the American engineer, chemist and mathematical physicist Josiah Willard Gibbs. It is the potential that a substance has to produce in order to alter a system.[1] In broadest… …   Wikipedia

  • Chemical reaction — Chemical reactions redirects here. For the 2007 television episode, see Chemical Reactions (Men in Trees). A thermite reaction using iron(III) oxide. The sparks …   Wikipedia

  • chemical industry — Introduction       complex of processes, operations, and organizations engaged in the manufacture of chemicals and their derivatives.       Although the chemical industry may be described simply as the industry that uses chemistry and… …   Universalium

  • Chemical kinetics — Reaction rate tends to increase with concentration a phenomenon explained by collision theory. Chemical kinetics, also known as reaction kinetics, is the study of rates of chemical processes. Chemical kinetics includes investigations of how… …   Wikipedia

  • chemical compound — Introduction  any substance composed of identical molecules consisting of atoms (atom) of two or more chemical elements (chemical element).       All the matter in the universe is composed of the atoms of more than 100 different chemical elements …   Universalium

  • chemical reaction — Any chemical process in which substances are changed into different ones, with different properties, as distinct from changing position or form (phase). Chemical reactions involve the rupture or rearrangement of the bonds holding atoms together… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”