Communication pubs.acs.org/jchemeduc
Adapting Bottles to Digital Burets for Small Volume Titrations Gregorio Cruz Villalón* Private Laboratory, San Pedro de Alcantara, 5, 06001, Badajoz, Spain S Supporting Information *
ABSTRACT: The modification of a plastic bottle to be adapted to an electronic digital buret is described. A hole is made at the bottom of the bottle that allows a little container with the titrant to be placed inside the bottle. Determinations with relatively small volume of titrant can be made with this system. This design is especially useful for titrations with expensive or unstable reagents, thus, saving costs and space storage in the laboratory. KEYWORDS: First-Year Undergraduate/General, Second-Year Undergraduate, Upper-Division Undergraduate, Analytical Chemistry, Laboratory Equipment/Apparatus, Titration/Volumetric Analysis
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polyethylene bottle (typically used for storage of commercial liquid reagents), we can place a small flask or any other container into the large bottle with the aspiration tube of the buret inside (see Figure 1). A stand helps to keep the low weight, top-heavy bottle stable. Making a hole the size of the bottle diameter in a board should provide stability to the system, but this can also be made using polystyrene foam. In this case, an extra weight, such as a lead pipe, must be fixed to the base. Commercial stands are also available.5 The modification described here is particularly useful for rinsing the buret when changing the titration solution.
lectronic digital burets offer the possibility of using large volumes of titrant with a precision comparable to or better
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HAZARDS Lead is a toxic metal, so use gloves when handling lead wire ASSOCIATED CONTENT
S Supporting Information *
Details of construction. This material is available via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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Figure 1. Modified setup to use small volumes of liquid with electronic digital burets.
than conventional glass burets.1−3 Digital readout (no meniscus or parallax error) and easy zero reset make its use less stressful to the user. The reason why these burets have not replaced conventional glass burets in undergraduate laboratories may be their relatively high cost.4 Electronic burets are generally attached to the neck of reagent bottles, usually with a volume of 1 L, using appropriate adapters. For small volumes of titrant, 100 mL or less, or for expensive or unstable reagents, large bottles are not suitable for operation. We have modified a plastic bottle to adapt to any recipient of relatively small volume to the buret. By cutting a circle (65 mm diameter) in the bottom surface of a © XXXX American Chemical Society and Division of Chemical Education, Inc.
REFERENCES
(1) Harris, D. C. Quantitative Chemical Analysis, 7th ed.;W.H. Freeman and Company: New York, 2007. (2) Roberts, J. L. J. Chem. Educ. 2002, 79, 941. (3) Williams, K. R. J. Chem. Educ. 1998, 75, 223. (4) For a comparison of prices, see Cole Parmer http://www. coleparmer.com/Category/Burettes_Burets/888 (accessed May 2013). (5) For an example of a commercial stand, see http://www.fishersci. com/ecomm/servlet/fsproductdetail_10652_607068__-1_0 (accessed May 2013).
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dx.doi.org/10.1021/ed400146k | J. Chem. Educ. XXXX, XXX, XXX−XXX
