Gravimetric Titrations in the Introductory Chemistry Laboratory A desirable feature of many recent laboratory manuals for the first course in college chemistry is an increased emphasis upon volumetric analysis. However, this can create problems in desk equipment where enrollments are large. Good volumetric apparatus is expensive. The Mohr buret, equipped with rubber tube, glass bead or pinch clamp, and glass tip, is somewhat l w costly but much less satisfactory because of the possibility of leakzge and bubble entrapment. The storage of burets between laboratory periods presents difficulties. A s i m ~ l eanswer to such uroblems lies in the techniaues sueeested .... bv Gitddis.' The fact that man" teachinn Isburntones nre now alrend? eqt~ippedw t h high spred, direct r e s d i ~ sit.glr , pull idarrcri sugyrcts that gmvimrtrir ~ is t~lrnrinn,wing inexpenwe plnstic bottles denrrves wiaer 3pplica1ion. A variety of pdyrthylr.r.r t l n ~ p p i nla,rrl+.i now qva~lnble.' l'hrir coat ir io low that ench st dent call t e provided wi~Ltwo or more i l r littlrexpewe. Our experience has shown that the average student can rapidly learn to do precise and accurate analytical work employing this simple technique. With a little care, duplicate acid-base titrations that agree within a few parts per ten thousand can be made even with top loading balances (3 mg reproducibility) as long as 20-30 g of titrant is used. Single pan balances of the general purpose, analytical type provide such precision vith ease. ROBERTCHRISTIAN, JR. WICHITA STATEUNNERSITY WICHITA,KANSAS
' GADDIS,S. W., J. CHEM.EDUC.,36, 290 (1959); ibid., 40, 324 (1963). 2 Some types that have been found to be satisfactory are F-11637 ( Z o z ) and F-11715 (50-ml) Dispensing Bottles, Bel-Art Products, Pequannock, N. J.; and P100-0060 (60-101) Dropper Bottle, Mallinckrodt Chemical Works, St. Louis, Mo.
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Journal of Chemical Education
