Answer:A balanced chemical equation provides a great deal of information in a very succinct format. Chemical formulas
provide the identities of the reactants and products involved in the chemical change, allowing classification of the
reaction. Coefficients provide the relative numbers of these chemical species, allowing a quantitative assessment
of the relationships between the amounts of substances consumed and produced by the reaction. These quantitative
relationships are known as the reaction’s stoichiometry, a term derived from the Greek words stoicheion (meaning
“element”) and metron (meaning “measure”). In this module, the use of balanced chemical equations for various
stoichiometric applications is explored.
The general approach to using stoichiometric relationships is similar in concept to the way people go about many
common activities. Food preparation, for example, offers an appropriate comparison. A recipe for making eight
pancakes calls for 1 cup pancake mix, 3
4
cup milk, and one egg. The “equation” representing the preparation of
pancakes per this recipe is
1 cup mix + 3
4
cup milk + 1 egg ⟶ 8 pancakes
If two dozen pancakes are needed for a big family breakfast, the ingredient amounts must be increased proportionally
according to the amounts given in the recipe. For example, the number of eggs required to make 24 pancakes is
24 pancakes ×
1 egg
8 pancakes = 3 eggs
Balanced chemical equations are used in much the same fashion to determine the amount of one reactant required to
react with a given amount of another reactant, or to yield a given amount of product, and so forth. The coefficients in
the balanced equation are used to derive stoichiometric factors that permit computation of the desired quantity. To
illustrate this idea, consider the production of ammonia by reaction of hydrogen and nitrogen:
N2
(g) + 3H2
(g) ⟶ 2NH3
(g)
This equation shows ammonia molecules are produced from hydrogen molecules in a 2:3 ratio, and stoichiometric
factors may be derived using any amount (number) unit:
2 NH3 molecules
3 H2 molecules or
2 doz NH3 molecules
3 doz H2 molecules or
2 mol NH3 molecules
3 mol H2 molecules
These stoichiometric factors can be used to compute the number of ammonia molecules produced from a given
number of hydrogen molecules, or the number of hydrogen molecules required to produce a given number of
ammonia molecules. Similar factors may be derived for any pair of substances in any chemical equation.
Step-by-step explanation: