Stoichiometry is derived from greek words, “Stoicheion'' means element and'' metron” means measure. Stoichiometry is the study of the quantitative aspects of a chemical change.
Stoichiometry is the calculation of the quantities of reactants and products involved in a chemical reaction. In stoichiometry we try to find the masses, volumes, number of particles, energies etc.. of reactants taking part in a chemical reaction and products formed.
1 mole of a gas = GMW of a gas = 22.4 L at STP
1 mole of a substance = GMW
Question 1: Calculate the number of atoms in 12 g of oxygen gas.
Molar mass of oxygen gas = 32.0 g/mol
Number of atoms in 1 oxygen gas molecule = 2
Question 2: Stoichiometry is derived from greek words, “Stoicheion” means element and“ metron” means _________.
Solution : Stoichiometry is derived from greek words, “Stoicheion” means element and“ metron” means measure
Answer : (d)
Question 3: 1 mole of any gas at STP occupies ___________.
(a) 32 litre
(b) 44 litre
(c) 22.4 litre
(d) All the above
Solution : 1 mole of any gas at STP occupies 22.4 litres.
Answer : (c)
There are some guidelines to calculate stoichiometry.
Assign 1 as the coefficient for the most complex species.
Balance the single-element species in last.
Eliminate fractional coefficients.
While balancing add coefficients only, do not change the chemical formula of any compound.
The number of atoms should be the same on both sides of the reaction.
For example- Let’s balance this equation using guidelines
The equation is not balanced as the number of N and O atoms is more on left (reactants) side
Assigning 1 coefficient in front of the most complex species
Balancing single element compounds
Stoichiometry is the quantitative relationship between the number of moles of different reactants and products in a chemical reaction. We know that a chemical equation must be balanced and must have the same number of different atoms in the reactants and products. To balance a chemical equation we add coefficients in front of reactants and products. These coefficients are known as stoichiometric coefficients and their study is called stoichiometry.
Stoichiometry problems can have multiple steps, which is not easy to memorize. Basic mathematics skills are required for stoichiometric calculations. Not understanding concepts can make it even more difficult. However, practicing solving problems after learning the concept well makes stoichiometry a lot more fun and interesting.
There are four simple steps to calculate stoichiometry: