A burette, or buret, is used to dispense precise and small amounts of liquid. Burettes have a stopcock, or spigot, at the end that allows substances to be dropped into other substances at slow rates. Like a water faucet for a hose on a house, turning the spigot more increases liquid flow, and turning it less reduces the amount of fluid that runs through the system.
Burettes deliver precise amounts of reactants needed to bring a reaction to its endpoint. Acid-based reactions in aqueous solutions are one example of what a burette is used for when dispensing precise amounts of liquid. If too much or too little of one substance is delivered, the reaction may not occur properly.
Measuring liquids is done by reading graduated marks on the burette before and after dispensing. A funnel is typically used to fill burettes to the top capacity to ensure chemicals are not spilled or wasted. Before dispensing liquids, notice if the burette's tip has an air bubble in it. Tap the side of the tip to get rid of the air bubble because bubbles may cause inaccurate readings. The end point of the amount of fluid dispensed by a burette should be arrived at slowly to prevent over-filling.