pipette
/ pi-PET /
Think of a precise drinking straw that, when filled to its line and let drain, always lets out the exact same mouthful every time. A pipette is that tool for chemistry: a slim glass or plastic tube for transferring a known, accurate volume of liquid.
A pipette is a calibrated tube you fill (usually by suction with a bulb, never by mouth) and then let drain to deliver a precise volume. A volumetric (bulb) pipette delivers one fixed volume marked on it; a graduated pipette has a scale so you can deliver various volumes.
It matters because accurate analysis often starts by transferring an exactly known portion of sample — the aliquot — and the pipette is the standard way to do that. Its honest limits: read at eye level to avoid parallax, and respect whether it is meant to drain fully or leave a small tip residue, since that detail is built into its calibration.
Before titrating, the analyst uses a 25.00 mL volumetric pipette to transfer exactly that volume of the sample solution into the flask — a measured aliquot ready to be titrated.
Transfer an exact, repeatable volume — the standard way to take an aliquot.
A volumetric pipette is calibrated 'to deliver' (TD), so a designed drop may remain at the tip — do not blow it out unless the pipette is marked to. This differs from a volumetric flask, which is calibrated 'to contain' (TC).