Glossary of Chemical Reaction Terms and Terminology

  • Chemical reaction: The transformation of one or more chemical substances that yields a unique and different substance
  • Single replacement chemical reaction: One of the types of a chemical reaction
  • Double replacement chemical reaction: One of the types of a chemical reaction
  • Combustion chemical reaction: One of the types of a chemical reaction
  • Decomposition chemical reaction: One of the types of a chemical reaction
  • Synthesis chemical reaction: One of the types of a chemical reaction
  • Endothermic chemical reaction: The type of chemical reaction that needs and uses heat
  • Exothermic chemical reaction: The type of chemical reaction that releases heat and energy.

Chemical reactions, simply defined, are the transformations of one or more chemical substances into a different substance. Chemical reactions, in contrast to transitions of states of matter, as detailed in the section immediately above, do transform substances into other substances; and transitions of states of matter yield the same substance, but, in a different state of matter like a solid, liquid or gas.

There are several kinds of chemical reactions and these five types of chemical reactions include:

  • Single replacement chemical reactions
  • Double replacement chemical reactions
  • Combustion chemical reactions
  • Decomposition chemical reactions
  • Synthesis chemical reactions

There are also two broad categories of chemical reactions, as listed below:

  • Endothermic chemical reactions
  • Exothermic chemical reactions

Endothermic chemical reactions are those chemical reactions that use heat and other energy; and, exothermic chemical reactions are those chemical reactions that release heat and energy.

Chemical reactions result from the interactions of the electrons surrounding the atom; these interactions can include both releasing and breaking of chemical bonds and also the forming of chemical bonds. The rates of chemical vary according to the type of reagents, reagent concentration, the concentration of the substrate, which is a chemical that reacts with a reagent to produce or create a product, temperature and pressure. Most often, chemical reactions speed up with more rapid reaction rates when heat is applied because increases of temperature and heat weaken the bonds between atoms.

Chemical reactions are graphically and mathematically displayed with chemical equations, such as the one below:

As seen from the equation CH4 + 2 O2 ' CO2 + 2 H2O, a coefficient of 2 must be placed before the oxygen gas on the reactants side and before the water on the products side in order for, as per the law of conservation of mass, the quantity of each element does not change during the reaction.

In the chemical equation shown above, the reagent CH4 is combined with the reagent 2O2, to yield CO2 and 2H2O. This chemical reaction moves in the direction of the arrow and the meaning of the arrow is "yields". Quite often, chemical reactions occur in several steps until the point of equilibrium is achieved.

The majority of chemical reactions are reversible and these chemical equations have a double arrow each of which is pointing to a different direction. The double arrow looks like this:

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