Boiling point elevation as an experiment in general chemistry

EXPERIMENT IN GENERAL CHEMISTRY. CREIG S. HOYT. Grove City College, Grove City, Pennsylvania. T he determination of molecular weights in solution...
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BOILING POINT ELEVATION AS AN EXPERIMENT IN GENERAL CHEMISTRY CREIG S. HOYT G r w e City College, Grove City, Pennsylvania

hes solvent consists of 15ml. (23.92 mams) of carbon tetrachloride, chosen because of its no&flammable character. A sample of 3 grams of solute, weighed to the nearest centigram, gives an elevation of such magnitude as to be accurately measured.

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The value of the boiling ~ o i n tconstant mas taken from the work of Hoyt and Fink1 and was corrected for

563

Horn AND FINK,J . P h y s Chem.. 41, 453 (10371.

JOURNAL OF CHEMICAL EDUCATION

564

barometric variation by their equation. This value for carbon tetrachloride is 5.03 a t a pressure of 760 mm. and the correction is 0.0013 per mm. difference in barometric pressure. The data in Table 1 was taken from the work of a class of 215 students, of which 203 were taken as having such accuracy as to serve as a measure of the precision of the method.

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of

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Sin- -Molecula~ An. Correct 127.2 128.06 152.2 152.13 235.0 235.86 147.2 146.96 246.3 244.10

Solule dm18 Naphthalene 48 Camphor 36 p-Dibrornhensene 21 54 44

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TABLE 1 WaiohI-

Mas. 132.8 160.1 242.0 156.8 252

Mi". 122.0 142.6 227.5 142.1 226

-DwiaIionPar A". Cant 2.06 1.6 4.24 2.8 6.51 2.8 1.88 1.3 5.46 2.2

We thank Dr. Carl K. Fink who prepared the illustration.