Define stoichiometry and stoichiometric calculation.

Explanation

The word .stoichiometry. is derived from two Greek words - stoicheion ( meaning element) and metron ( meaning measure).
Stoichiometry, thus, deals with the calculation of masses ( sometimes volumes also) of the reactants and the products involved in a chemical reaction.
Before understanding how to calculate the amounts of reactants required or the products produced in a chemical reaction, let us study what information is available from the balanced chemical equation of a given reaction.
Let us consider the combustion of methane. A balanced equation for this reaction is given as :
`CH_(4(g))+2O_(2(g)) rarr CO_(2(g))+2H_(2)O_((g))`
Here, methane and dioxygen are called reactants and carbon dioxide and water are called products.
Note that all the reactants and the products are gases in the above reaction and this has been indicated by letter (g) in the brackets next to its formula, Similarly, in the case of solids and liquids, (S) and (l) are written respectively.
The coefficients 2 for `O_(2)` and `H_(2)O` are called stoichiometric coefficients. Similarly the coefficient for `CH_(4)` and `CO_(2)` is one in each case.
Thus, From these relationships, the given data can be interconverted as follows:
`"mass" hArr "mole" hArr "no. of molecules" ("mass")/("valume") = "pensity"`