Chemistry progressed from an art to a science when, in the course of performing experiments, scientists began to measure the quantities of each substance consumed in a chemical reaction and the amounts of resulting substances produced. Simply put, such is the importance of stoichiometry in chemistry. Stoichiometry concerns itself with two vital aspects of weight calculations: 1) description of compounds in terms of the elements that combine to form them, and 2) quantitative consideration of the relative amounts of reagents that are consumed or produced in chemical reactions.
The actual yield of a reaction is usually less than its theroretical yield. Percent yield refers to calculation of actual yield as a percentage of theoretical (maximum) yield. An idea of percent yield is central to successfully drive a chemical synthesis or process, minimizing the wastage of reagents, products fuel and labour. At the same time it minimizes atmospheric stress caused by a particular chemical process. The percent yield and its control are of great economic and industrial relevance too.