Introduction to Titration

A titration turns a question you can't measure directly — how concentrated is this acid? — into one you can: how much volume did it take? You load a buret with a solution of known molarity, the titrant, and slowly drip it into a flask holding a measured volume of the unknown solution, the analyte. A few drops of indicator sit in the flask too, waiting to change color. As titrant drips in, the reaction consumes both reactants. Near the equivalence point only a tiny bit of unreacted analyte remains, so one more drop of titrant suddenly has nothing left to react with and shifts the solution's condition enough to flip the indicator's color — that's why the change looks instant rather than gradual.

The setup matters because every volume has to be trustworthy. You rinse and fill the buret with titrant, record the starting volume, and measure out a known volume of analyte into the flask with a pipet. You add indicator, then add titrant drop by drop, swirling, watching for the color change to appear and persist for about 30 seconds. At that point you record the final buret reading; the difference is the volume delivered. From there it's stoichiometry: moles of titrant at that volume equal moles of analyte, using the balanced equation's mole ratio, and dividing by the analyte's known volume gives its molarity.

This is the same mole-to-mole bookkeeping from balancing and stoichiometry, just run in reverse to solve for an unknown concentration instead of an unknown mass. It sets up later work with weak acids and bases, where the equivalence point isn't at pH 7 and choosing the right indicator becomes its own problem.