Solve stoichiometry in solutions.
A titration determines an unknown concentration by reacting it exactly with a standard of known concentration. Moles of titrant come from concentration times volume in litres; the balanced equation's mole ratio converts those into moles of analyte; and dividing by the aliquot volume gives the analyte's concentration. The mole ratio is where most errors creep in — neutralising sulfuric acid with sodium hydroxide consumes two moles of base per mole of acid.
Titration stoichiometry
titrant moles = M x V(L); analyte moles = titrant moles x mole ratio; analyte molarity = analyte moles / analyte volume in litres
It comes from the balanced equation. HCl with NaOH is 1:1. H2SO4 with NaOH needs two base per acid, so entering the acid as analyte and base as titrant gives a ratio of 0.5. Permanganate against iron(II) in acid is 5 iron per permanganate.
Because a single reading carries indicator and endpoint error. Standard practice is a rough titration followed by at least three concordant titres within 0.10 mL, then averaging those for this calculation.
Yes — it appears directly in the denominator, so it should be delivered with a pipette rather than a measuring cylinder. A 1 percent error in the aliquot is a 1 percent error in the final concentration.