The word “ stoichiometry” is derived from the Greek word “stoikhein” meaning element and “metron” meaning measure. Stoichiometry refers to the calculation of and quantitative study of reactants and products in a chemical reaction. The study of the relationship between reactants and products is called stoichiometry. Jeremias Richter was the first one to throw light on this concept. The concept mainly deals with the number and measurement of elements involved in the chemical equation.
There must be a correlation between the reactants and products for the reaction to take place. Following are the steps to be followed to solve a stoichiometric problem given:
- Balancing the given chemical equation
- Conversion of given units onto moles
- Calculate the number of moles yielded by the reaction or substance
This process also helps in giving many other data from the chemical reaction. Using stoichiometry we also get to know about the following things:
- Mass of reactants
- Mass of products
- Molecular weight of the compounds formed
- Formulas of elements involved in the chemical reaction
- Chemical equation and balancing them
Let us consider the following balanced chemical reaction:
3Fe(s) + 4H2O(l) ⇾ Fe3O4 (s)+ 4H2 (g)
Using the above information we studied the quantitative information that can be derived from the given equation is:
- 3 mole of iron (Fe) reacts with 4 moles of water molecule(H2O) to give the product of one mole of Ferrous oxide (Fe3O4) and 4 moles of Hydrogen (H2).
- We know that the molecular mass of Fe = 56
3 atoms of Fe are involved= 56 X 3 =168g
- Molecular mass of water= 18
4 molecules of water are involved = 18 X 4 = 72g
- We obtain the product Fe3O4 whose molecular mass is 231g and hydrogen
Hence the whole reaction in short can be written as
168g of Fe reacts with 72g of H20 to yield 231g of Fe3O4 and 8g of H2 gas.
The most common method used in volumetric analysis for measuring the quantity of a substance is titration. The process of identifying the amount of solution required to react entirely with the volume of another solution is referred to as titration. For the process of titration, we require a titrant-solution whose strength is known, a titrate- solution whose strength is to be estimated, and an indicator- which shows that the reaction is complete.
The following are the different types of titration involved in volumetric analysis:
- Acid-base Titration: An acid solution of known concentration is titrated against a strong base, the concentration of acid can be calculated and the neutralization reaction takes place in this process.
- Redox Titration: The oxidizing or reducing agents are titrated against strong reducing or oxidizing agents respectively.
- Precipitation Titration: A precipitate is formed when the titration reaction occurs.
- Complexometric Titration: A coloured complex is formed which is used to indicate the end of the titration reaction.
Stoichiometry and titration play a vital role in estimating and calculating the amount of substance formed in the reaction. This helps in knowing and understanding the amount of reactants and products required to form the important chemical compounds.