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Chemical Equation

Conventions And Symbols, A Few ExamplesApplications

Chemical equations reveal the chemical species involved in a particular reaction, the charges and weight relationships among them, and how much heat of reaction results. Equations tell us the beginning compounds, called reactants, and the ending compounds, called products, and which direction the reaction is going. Equations are widely used in chemical engineering, they serve as the basis for chemical synthesis, reactor design, process control, and cost estimate. This allows chemical process engineers to prepare ahead of time for on-line production.

It is fairly difficult to take a few chemical compounds and derive chemical equations from them, because many variables need to be determined before the correct equations can be specified. However, to look at a chemical equation and know what it really means is not as difficult. To achieve this, there are certain conventions and symbols which we always have to keep in mind. Now let's start with a general chemical equation, aA + bB Δ→ cC + dD↑, to explain those conventions and symbols, and few examples will then be given and discussed.

Because the stoichiometric coefficients are unique for a given reaction, chemical equations can provide us with more information than we might expect. They tell us whether or not the conversion of specific products from given reactants is feasible. They also tell us that explosive or inflammable products could be formed if the reaction was performed under certain conditions.

Pang-Jen Kung


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—A pure substance that consists of two or more elements, in specific proportions, joined by chemical bonds. The properties of the compound may differ greatly from those of the elements it is made from.

Heat of formation, ΔHf°

—The heat involved for the formation of 1 mole of a compound that is formed from the elements which make up the compound.

Oxidation-reduction reaction

—A chemical reaction in which one or more atoms are oxidized, while one or more other atoms are reduced.

Standard potential

—The electrochemical potential (volts) with respect to the standard state which is a measure for the driving force of a reaction.


—Deals with combining weights of elements and compounds.

Additional topics

Science EncyclopediaScience & Philosophy: Ephemeris to Evolution - Historical Background