In the Laboratory edited by
Cost-Effective Teacher
Harold H. Harris University of Missouri—St. Louis St. Louis, MO 63121
In Praise of Latex Gloves Francisco J. Arnáiz Laboratorio de Química Inorgánica, Universidad de Burgos, 09001 Burgos, Spain;
[email protected] Latex gloves, and in general flexible gloves, are inexpensive ubiquitous items whose utility in chemistry labs goes far beyond their primary mission (hand protection and protection of materials from grease and sweat on hands). In a previous paper we described the use of a latex finger to facilitate the filling of capillaries in an inert atmosphere (1). Here we mention some typical situations in which latex gloves can aid in overcoming difficulties that might arise in common labs. The Transfer of Air-Sensitive Compounds from Bottles to Reaction Flasks
Figure 1. Use of latex glove in the transfer of air-sensitive compounds from bottles to reaction flasks.
Figure 2. “Dry chamber” for handling air-sensitive materials.
1354
The glove can be tightly adapted to 500– 1000-mL commercial bottles (Fig. 1). It is sufficiently flexible to allow for the opening and closing of the bottle while a stream of inert gas is flowing through two of the fingers. The pickup of liquid samples can be made by syringe in one of the remaining fingers. For solid samples, vials or tubes—previously inserted in the fingers or connected later—can be filled with ease. Alternatively, when the solid is glove friendly, the transfer can be made directly after cutting and adapting one of the fingers to the reaction flask. In a similar manner small bottles and flasks can be handled inside a “dry chamber” prepared by adjusting a glove to an appropriate vessel, crystallizing dish, or a glass mortar (Fig. 2).
The Grinding of Solids Grinding is sometimes a tedious operation, especially when the solid is prone to jump as, for example, the familiar crude CuSO4⭈5H2O. A piece of paper or cloth is habitually placed on the mortar to avoid spills. However, considerable advantage is gained by adapting a latex Figure 3. Use of a latex glove to glove bearing the pestle hold the pestle when grinding a lodged in the central finger solid. (Fig. 3). The usefulness of this arrangement is unquestionable for powdering hygroscopic products. I regularly use it to grind potassium hydroxide (finely powdered KOH is the deprotonating–dehydrating agent of choice for a number of interesting syntheses in nonaqueous solvents [2]). In this way the required product is readily prepared, easily dispensed through the fingers, and preserved sufficiently dry in the mortar for several days. The Replacement of Multinecked Reaction Flasks with Common Vessels This is possible provided that all operations are conducted at a pressure close to ambient and the compatibility of latex with the reacting system has been previously tested. The glove is adapted to a 250–500 mL-vessel and the fingers permit the connection to the inert gas and a variety of accessories (e.g., burets, funnels, electrodes, mechanical stirrers). Many reactions, conductivity measurements, and titrations involving air-sensitive products can be successfully carried out in this manner, praise to latex gloves. NOTE: In case the glove is coated inside with talc powder, it should be cleaned (inversion is advisable) before use. Literature Cited 1. Arnáiz, F. J. J. Chem. Educ. 1996, 73, A102–A103. 2. Jolly, W. J. Inorg. Synth. 1968, 11, 113.
Journal of Chemical Education • Vol. 77 No. 10 October 2000 • JChemEd.chem.wisc.edu
