What is a titration?

Answer 1

A titration is the use of carefully measured amounts of a known solution to determine the concentration of another. They often involve acid-base neutralisation or oxidation-reduction reactions (examples would be sodium hydroxide with hydrochloric acid, or permanganate with an iron solution). The main part of the system is the burette, a large graded tube with a controllable variable nozzle at its end. This nozzle is used to add different amounts with great precision to the solution being tested, so that an exact reading can be made - if done correctly, the titration's accuracy is limited only by the scale on the burette. A sample of the test solution (collected using a pipette with a known volume and high degree of accuracy; the sample is called an aliquot) is placed in a container, usually a conical flask, under the burette. The burette is filled with known solution, i.e. one where the concentration is know to another high degree of accuracy. The two are mixed slowly and allowed to react - for acid-base titrations an indicator will be added to the flask, for redox the solution which will change colour is put in the burette. This is continued slowly until the solution will barely react with that from the burette. At this point the amount of solution taken from the burette is recorded. Ideally, the next slightest drop of burette solution will cause a change in colour of the solution that does not change at all. If not, the new recording is made and the last step repeated. This amount is a titre. The whole experiment is repeated several times. The data is collected and averaged out. From this, an amount of known solution used, an amount of tested solutio used and eventually a concentration can be found.