Stoichiometric calculations

Question 1

What is stoichiometry?

Answer 1

Stoichiometry is the study of quantitative relationships involved in chemical reactions.

Question 2

Theoretical yields can be calculated and compared with actual yields leading to determining the percentage yield. What can the percentage yield be reduced by?

Answer 2

The percentage yield is reduced by, for example: 
 mass transfer or mechanical losses   
purification of product   
side reactions   
equilibrium position   
purity of reactants