Question

How can stoichiometry be used?

Answer 1

A balanced chemical equation tells us about the exact number of quantities (called as moles) involved in a chemical reaction. Through these quantities, we can calculate the amount of unknown entity that is needed for practical or analytical use.

Complete answer:
Stoichiometry is one of the branches of chemistry that helps us to deal with the relative amount of the reactants and products that are involved in a chemical reaction. Through stoichiometric calculations we can determine the unknown quantities or the quantities that we need in a chemical reaction.
For instance, in a reaction of hydrogen and oxygen that produces water as,
$2{{H}_{2}}+{{O}_{2}}\to 2{{H}_{2}}O$
Here, 2 moles of hydrogen ${{H}_{2}}$, and 1 mole of oxygen ${{O}_{2}}$ produces 2 moles of water ${{H}_{2}}O$. This tells that for every 2 mole of water, 1 mole of ${{O}_{2}}$ and 2 mole of ${{H}_{2}}$ is required. This can be represented by the ratios,
$\dfrac{1\,mol\,{{O}_{2}}}{2\,mol\,{{H}_{2}}O}$ Or $\dfrac{2\,mol\,{{H}_{2}}}{2\,mol\,{{H}_{2}}O}$ and vice versa.
Now, if we need to calculate the number of moles of water produced from 6 moles of oxygen, then the stoichiometric calculation will be applied as:
6 moles oxygen will produce water= $6\,mol\,{{O}_{2}}\times \dfrac{2\,mol\,{{H}_{2}}O}{1\,mol\,{{O}_{2}}}$ = 12 moles of ${{H}_{2}}O$(water).
This example shows how to obtain the number of moles using stoichiometry.
Hence, stoichiometry is useful in taking measurements for quantities that are unknown to us.

Note:
While dealing with stoichiometric problems, it is necessary to balance the chemical equation. If the equations are not balanced properly, then it may lead to mistakes in the calculations and the answer would differ greatly.