Burette - wikipedia Burette A burette ( also buret ) is a laboratory equipment used in analytical chemistry for the dispensing of variable amount of a chemical solution and measuring that amount at the same time. It is a long, graduated glass tube, with a stopcock at its lower end and a tapered capillary tube at the stopcock 's outlet. The flow of liquid from the tube to the burette tip is controlled by the stopcock valve. There are two main types of burette ; the volumetric burette and the Piston burette or Digital burette. A volumetric burette delivers measured volumes of liquid. Piston burettes are similar to syringes, but with a precision bore and a plunger. Piston burettes may be manually operated or may be motorized. A weight burette delivers measured weights of liquid. Contents 1 Overview 2 Volumetric Burette 2.1 Burette reading 2.2 Specification 3 Digital Burette 4 History 5 Additional images 6 References 7 External links Overview A burette is a volumetric measuring glassware which is used in analytical chemistry for accurate dispensing of variable, and for measuring the volume of a liquid, especially of one of the reagents in a titration. In a titration of an acid and base solution, the burette can be filled with acid. By turning the tap in a perpendicular direction, the tap can be opened, which then allows the acid in the tube to be able to be added in a stream or drop by drop into a flask. The experiment is taken out by gradually filling a liquid samples. Titrant or titrated solution is a good example. Burette support the process by its long narrow tubed with a stopcock at the taper end. The addition will halt when there the correspondence point is set up. Burettes can perform titrations precisely for delivering a volumetric measurement of a fluid. The burette tube carries graduated marks from which the dispensed volume of the liquid can be determined. Compared to pipette, greater precision can be attained by using a burette. The burette is used to measure a volume of a substance in a specific amount, but different from measuring cylinder as its graduations measure from top to bottom. Therefore, the difference between the starting and the final volume is equal to the amount dispensed. The precision and control of the burette over other means of adding solution is beneficial for using in titration in order to add titrant to the titrated solution. Volumetric burette Volumetric burette can be glass or plastic stright tube with a graduation scale. At the tip of burette, there are a stopcock and valve to control the flow of the chemical solution. The barrel of the stopcock can be made of glass or the plastic PTFE. Stopcocks with glass barrels need to be lubricated with vaseline or a specialized grease. Burettes are manufactured for specific tolerances, designated as class A or B and this also is etched on the glass. Black stripped technique Burette reading The amount of solution added in or drained out needed to be read correctly by observing at eye level straight to the bottom of `` Meniscus '' for most solutions. Before reading the data, the bubbles must all been removed from the Burette otherwise the data will be inaccurately measured. Also, reading the data at the eye level means looking straight at the bottom of the meniscus. The initial and final volumes collected will be calculated for the difference in volume which equal to the total volume of solution drained out of the Burette. The difference in volume can be calculated by taking the difference of final volume and initial volume Using the Burette with a colorless solution is sometimes difficult to observe the bottom of the meniscus so Black Strip Technique can help to accurately observe and measure the number on the scale. Moreover, the number should be reported in two decimal places, which can be done more easily by using the Black strip Technique. The black strip can be written with pen on the normal white paper or it can be printed it out. However, it is necessary to use white color paper as the background, in order to make the scale readable. Specification Specification or product specification is used as an identification of volumetric burette for example nominal volume, volume unit, error limit, accuracy class of the burette and manufacture 's related details. Specification is directly association with the usage of each laboratory equipment including burette. Therefore, it is necessary to be able to understand each of specification in details in order to perform the accurate experiment. Nominal volume, error and units are the basic knowledge in order to distinguish the amount of solution delivered from the burette in unit of ml or cm. Another specification for burette is called calibration marked as TD or Ex stand for `` Calibration to Deliver ''. It indicates that this burette is better used to delivery purpose which the amount will be correspond to the volume as specified The accuracy classes of equipment also shown in the specification of burette as well and it includes class A and class B. Class A is more preferred than Class B when volumetric accuracy is important for the accuracy of the experiment with accuracy up to 0.1 percent compared to 0.2 percent in Class B burette. Specification ( on top of the burette ) Digital burette Digital burettes are based on a syringe design. The barrel and plunger may be made of glass. With liquids that corrode glass, including solutions of alkali, the barrel and plunger may be made of polyethylene or another resistant plastic material. The barrel is held in a fixed position and the plunger is moved incrementally either by turning a ratcheted wheel by hand, or by means of a step motor. The volume is shown on a digital display. A high - precision syringe may be used to deliver very precise aliquots. Motorized Digital Burettes may be controlled by a computer ; for example, a titration may be recorded digitally and then subject to numerical processing to find the titer at an end - point. History The first burette was invented in 1845 by the French chemist Étienne Ossian Henry ( 1798 -- 1873 ). In 1855, the German chemist Karl Friedrich Mohr ( 1806 -- 1879 ) presented an improved version of Henry 's burette, having graduations inscribed on the tube of the burette. The word `` burette '' was coined in 1824 by the French chemist Joseph Louis Gay - Lussac ( 1778 -- 1850 ). Additional images Meniscus Burette with Ring stand plastic stopcock used in glass volumetric burette References Jump up ^ Mendham, J. ; Denney, R.C. ; Barnes, J.D. ; Thomas, M.J.K. ( 2000 ), Vogel 's Quantitative Chemical Analysis ( 6th ed. ), New York : Prentice Hall, ISBN 0 - 582 - 22628 - 7 Section 3.12, p. 79, `` Burettes '' Jump up ^ Redman, H.N. ( 1963 ). `` An improved type of weight burette for use in volumetric analysis ''. Analyst. 88 : 654 -- 655. Bibcode : 1963Ana... 88... 654R. doi : 10.1039 / AN9638800654. Jump up ^ Chauhan, Yogesh. `` Burettes, Laboratory Glassware ''. EzineArticles. Missing or empty url = ( help ) ; access - date = requires url = ( help ) Jump up ^ `` Titration ''. britannica. 2017. Jump up ^ `` Burettes ''. chem.yorku.ca. Jump up ^ `` Acids and Alkalis ''. gcsescience. Jump up ^ Skoog, D.A. ; West, D.M. ; Holler, F.J. ( 2000 ). Analytical Chemistry : An Introduction, seventh edition. Emily Barrosse. pp. 44 -- 45. ISBN 0 - 03 - 020293 - 0. Jump up ^ `` Burette - Preproom.org ''. Retrieved 2017 - 05 - 23. Jump up ^ `` Laboratory volumetric glassware used in titration - burette, pipette, ASTM E287 - 02 standard specification ''. www.titrations.info. Retrieved 2017 - 05 - 23. Jump up ^ Henrickson, Charles H. ; Byrd, Larry C. ; Hunter, Norman W. ( 2000 ). `` 1 ''. A laboratory for General, Organic & Biochemistry. The Mcgraw - Hill Companies, Inc. Jump up ^ Sienko, Michell J. ; Plane, Robert A. ; Marcus, Stanley T. ( 1984 ). Experimental Chemistry. McGraw - Hill. Inc. p. 16. ^ Jump up to : Seely, Oliver. `` Helpful Hints on the Use of a Burette ''. www.csudh.edu. Retrieved 2017 - 06 - 09. Jump up ^ `` LabWare LIMS v6 Help ''. limshelp.labware.com. Retrieved 2017 - 06 - 20. Jump up ^ `` Measuring Volume ''. www.harpercollege.edu. Retrieved 2017 - 06 - 20. Jump up ^ `` Burette -- Jaytec Glass ''. www.jaytecglass.co.uk. Retrieved 2017 - 06 - 20. Jump up ^ Henry, O. ( 1845 ). `` Nouvelles expériences sur l'essai des potasses du commerce et appareil dit potassimètre pour l'effectuer '' ( New experiments on the assay of commercial potash and an apparatus called a `` potassimeter '' to perform it ). Journale de Pharmacie et de Chimie. 3rd series ( in French ). 7 : 214 -- 222. A sketch of Henry 's burette appears on p. 218. From p. 218 : `` AC est un tube de verre d'une longuere de 60 centimètres environ, et d'un diamètre de 4 millimètres à peu près. En A se trouve un entonnoir de verre soudé ou adapté à volunté ; et en B un petite robinet en cuivre terminé par un tube capillaire. Ce robinet s'adjuste au tube par un bon bouchon et avec de la cire à cacheter. Le tube AB est fixé par deux crochets au long d'une échelle inscrite sur une planche, et cette échelle est divisé en 100 parties égales. Le tout est supporté par un pied qui permet de placer le tube AB au - dessus du vase M contenant le sel de potasse à essayer. '' ( AC is a glass tube ( that 's ) about 60 cm. long, and nearly 4 mm. in diameter. At A, a glass funnel is joined or fitted as desired ; and at B ( there is ) a small copper valve ending with a capillary tube. This valve is fitted to the tube by a good cap and with sealing wax. The tube AB is fixed by two brackets along a scale ( that 's ) inscribed on a plate, and this scale is divided into 100 equal parts. The whole is supported by a base that permits placing the tube AB above a vase M containing the potassium salt to be assayed. ) Jump up ^ See : Szabadváry, Ferenc ( 1986 ). `` The history of chemical laboratory equipment ''. Periodica Polytechnica Chemical Engineering. 30 ( 1 -- 2 ) : 77 -- 95. See p. 87. Szabadváry, Ferenc ( 1966 ). History of Analytical Chemistry. Translated by Gyula Svehla. Oxford, England : Permagon Press. p. 237. Christophe, R. ( 1971 ). `` L'analyse volumétrique de 1790 à 1860. Caractéristiques et importance industrielle. Evolution des instruments '' ( Volumetric analysis from 1790 -- 1860. Characteristics and industrial importance. Evolution of instruments. ). Revue d'histoire des sciences ( in French ). 24 ( 1 ) : 25 -- 44. From p. 38 : ``... il préfigure bien ses descendants actuelles... '' (... it ( i.e., Henry 's burette ) foreshadows well its modern descendants... ) Jump up ^ Mohr, Karl Friedrich ( 1855 ). Lehrbuch der chemisch - analytischen Titrirmethode..., part 1 ( Textbook of analytical chemistry titration methods... ) ( in German ). Braunschweig, ( Germany ) : Friederich Vieweg und Sohn. pp. 2 -- 20. Page 3 shows Mohr 's burette ; page 12 shows a burette with a glass stopcock ( Glasshahn ). Jump up ^ Gay - Lussac, Joseph Louis ( 1824 ). `` Instruction sur l'essai du chlorure de chaux '' ( Instructions on the assaying of chlorinated lime ). Annales de chimie et de physique. 2nd series ( in French ). 26 : 162 -- 175. On p. 171, Gay - Lussac describes various figures that appear in a plate ( illustration ) that accompanies the article. From p. 171 : `` I, burette destinée à mesurer la teinture d'épreuve :... '' ( I, burette intended to measure the test dye :... ) External links Using a Burette from ChemLab at Dartmouth College demonstrating how to use a burette correctly Use of the Buret Laboratory equipment General Heaters Dryers Alcohol burner Bunsen burner Desiccator Heating mantle Hot plate Lab oven Kiln Meker - Fisher burner Striker Teclu burner Water bath Vacuum dry box Mixers Shakers Chemostat Homogenizer Liquid whistle Magnetic stirrer Mortar and pestle Shaker Sonicator Static mixer Stirring rod Vortex mixer Wash bottle Stands Clamps Holders Beaker clamp Clamp holder Tripod Burette clamp Extension clamp Flask clamp Funnel support Iron ring Pinch clamp Retort stand Screw clamp Test tube holder Test tube rack Wire gauze Lab drying rack Containers Storage Agar plate Cryogenic storage dewar Incubator Laminar flow cabinet Microtiter plate Petri dish Picotiter plate Refrigerator Weighing boat Weighing dish Other items Aspirator Autoclave Balance brush Cork borer Crucible Filter paper File Forceps Centrifuge Microscope Pipeclay triangle Spectrophotometer Splint Stopper Scoopula Spatula Test tube brush Wire brush Inoculation needle Inoculation loop Glassware Apparatus Dean - Stark Soxhlet extractor Kipp 's Bottles Boston round Pycnometer Condensers Cold finger Liebig Dishes Evaporating Petri Watch glass Flasks Büchner Vacuum ( Dewar ) Erlenmeyer Fernbach Fleaker Florence Retort Round - bottom Schlenk Volumetric Funnels Büchner Hirsch Dropping Separatory Measuring devices Burette Conical measure Cuvette Eudiometer Graduated cylinder Ostwald viscometer Pipette Pipette ( dropper ) Tubes Boiling Drying Cragie Ignition Nuclear magnetic resonance ( NMR ) Test Thiele Thistle Other items Beaker Gas syringe Vial Analytical chemistry Compositional AutoAnalyzer CHN analyzer Colorimeter Inductively coupled plasma ( ICP ) device Gas chromatograph ( GC ) Liquid Chromatograph ( LC ) Mass spectrometer ( MS ) pH indicator pH meter Microscopy Scanning electron microscope ( SEM ) Transmission electron microscope ( TEM ) Thermochemistry Calorimeter differential scanning Melting point apparatus Thermometer Thermogravimetric analyzer ( TGA ) Other items Analytical balance Colony counter Spiral plater Nuclear magnetic resonance ( NMR ) instrument Plate reader Electronics Ammeter Current source Function generator Galvanostat Multimeter Network analyzer Oscilloscope Pulse generator Potentiostat Spectrum analyzer Time - domain reflectometer Voltage source Voltmeter Safety Personal protective equipment ( PPE ) Lab coat Face shield Respirator Rubber apron Safety shower Eye and hand Acid - resistant gloves Eyewash station Glove box Medical gloves Nitrile gloves Safety glasses Safety goggles Other items Acid ( solvent ) cabinet Biosafety cabinet Fire blanket Fire extinguisher Fume hood Instruments used in medical laboratories Retrieved from `` https://en.wikipedia.org/w/index.php?title=Burette&oldid=836422977 '' Categories : Laboratory equipment Volumetric instruments French inventions Hidden categories : Pages using web citations with no URL Pages using citations with accessdate and no URL CS1 French - language sources ( fr ) CS1 German - language sources ( de ) Talk Contents About Wikipedia Afrikaans Català Čeština Dansk Deutsch Eesti Ελληνικά Español Euskara فارسی Français Galego 한국어 Hrvatski Ido Bahasa Indonesia Italiano עברית Қазақша Magyar Bahasa Melayu Nederlands 日本 語 Occitan Polski Português Română Русский Simple English Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் తెలుగు ไทย Українська 中文 32 more Edit links This page was last edited on 14 April 2018, at 18 : 46. 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Question: to how many decimal places should the volume of a liquid in a burette be recorded
Answer: two