Final answer:
The volume and molarity of titrant in a titration, combined with reaction stoichiometry, allow us to calculate the number of moles and therefore the concentration of an unknown sample. Stoichiometry also facilitates mass-volume conversions in reactions involving gases, thanks to the molar volume at STP.
Step-by-step explanation:
From the volume and molarity of a titrant and the stoichiometry of a reaction, we can calculate the number of moles of a reactant in an unknown sample. During a titration, especially an acid-base titration, the volume and concentration (molarity) of the titrant added to reach neutrality are used to determine the moles of reactant present in the sample, using the relationship concentration × volume = moles. The stoichiometry of the reaction indicates the mole-to-mole relationships between reactants and products, which is critical for calculating the unknown concentration. Examples include neutralization reactions where acids and bases react to form water and a salt, and the titrant volume required to reach the equivalence point is measured to find the moles of analyte.
If the reaction involves gases, we might also apply the concept of molar volume at standard temperature and pressure (STP), which is 22.4 liters per mole, to transition between volume and moles. Both quantitative chemical analysis techniques like titrations and gravimetric analysis are founded on stoichiometry to determine concentrations or masses of substances accurately.