1: Chemical Reactions and Balancing Reaction Equations
Chemical reactions can occur if sub-microscopic particles, such as atoms, molecules and ions approach each other closely or collide. Bonds between atoms in the starting molecules are broken and new bonds and compounds appear.
The transformation is represented by a chemical equation like:
A + B → C
, with A and B as reactants and C as product.
Balancing Reaction Equations
In this and the following subunit you will learn about the concept of stoichiometry. Stoichiometry is the calculation of the quantities of elements or compounds involved in chemical reactions.
As a direct consequence of the law of conservation of matter, the number of atoms of all elements should be equal on the left and right hand side of a reaction equation. Thus a chemical equation should be balanced with the help of stoichiometric coefficients.
(N.B. As a rule the coefficients in chemical equations should be whole numbers).
Example: Balancing Reaction Equations
An example is the reaction between oxygen (O2) and the organic compound glucose, C6H12O6, which forms carbon dioxide (CO2) and water (H2O). This reaction takes place when glucose is degraded by microorganisms in the presence of air or when glucose is combusted.
The balancing of the equation for this chemical reaction proceeds as follows:
One molecule of C6H12O6 reacts with 6 oxygen molecules, to yield 6 carbon dioxide and 6 water molecules.