# Stoichiometric Calculations Based On Chemical Formulas

Stoichiometry is an integral part of chemistry that involves the relationship between product and reactants in a chemical reaction and other words, stoichiometry means the measurement of elements. To understand Stoichiometric calculations, it’s necessary to comprehend the relationship between reactants and products taking place in a chemical reaction. For a reaction to being balanced, both sides of the equation must have the same number of elements. To adjust the number of each element on both sides of the reaction, we use stoichiometric coefficients, and it is the number written of atoms to balance the reaction. Now, we can discuss the conversion factors to solve stoichiometric problems. Steps to be followed are:

• First, we need to balance the given equation.
• The given substance should have the unit as a mole.
• Calculate the number of moles

Stoichiometric Calculations

Stoichiometric Calculations are mostly based on chemical formulas.

1. Formula Mass: It is defined as the sum of the atomic weights of the each atom present in the molecule of the substance. For example formula mass of Na2S is calculated as 2(23) + 1(32) = 78
2. Avogadro number: Avogadro’s number is defined as the number of particles present in one mole of substance. It is defined as a number of atoms present in exactly 12g of C-12.Avogadro number is valued as 022 × 1023.
3. Molar Mass: It is defined as the sum of the total mass of all the atoms that make up a molecule per mole.

The mole ratio of reactants and products can be explained with the help of the following reaction:

$2Na~ + ~2HCl ~\rightarrow~ 2NaCl~ + ~H_2$

From the above reaction, we can say that 2 moles of Na react with 2 moles of HCl to form 2 moles of NaCl ( Sodium Chloride) and 1 mole of H2. Hence for a given amount of sodium let us say x mole, the x mole of NaCl will be formed on reaction with x mole of HCl and the hydrogen gas produced will be x/2 moles.