A LECTURE EXPERIMENT TO DEMONSTRATE THE ADSORPTION OF GASES BY SOLIDS1 R. R. McLAUGHLIN and D. AZIZ University of Toronto, Toronto, Canada
IT
WAS felt that the demonstration of the adsorption of gases by solids in an unequivocal and vivid manner would strengthen the discussion of this subject with chemical engineering students. The experiment described below does this by causing a pressure drop, due to adsorption, of the order of 200-300 mm. of Hg to take place in a few seconds. This is plainly indicated by a mercury manometer. Two lecture experiments illustrating adsorption of gases by solids are recorded in the but the one described is believed to be sufficiently different to warrant description.
APRARATUS
A, 1-liter Pyrex round-bottomed flask B, 2.5 cm. diam. X 24 cm. long tube, with T (24/40) at K C, similar to B D , graduated tube E, stopcock lubricated with ether-insoluble lubricant (starch-glycerol gel)" F, G, H, J, stopcocks lubricated with silicone high vacuum lubricant L, mercury manometer connected to G with pressure tubing A[, T (19/38) The whole apparatus can be mounted on one heavy buret stand for ease of transportation. Preparation of Apparatus for Use. Place about 45 grn. of 1 4 6 0 mesh silica gel containing about 20 per cent moisture in B, cover lightly with plug of glass wool or glass cloth, surround B with an oil bath, bring to and maintain a t 150°C. while evacuating the system through D to a constant pressure of about 0.2 mm. with a mechanical pump (about 2 hours). Close E. On cooling to room temperature the apparatus is ready for use. Demonstration. (1) With E closed and all other stopcocks open the manometer will indicate virtually zero pressure in the system. (2) Close F, H, and J (3). Place ether in D and by opening E cautiously admit to the system 1.0 to 2.5 ml. of ether. Close E. (4) Open F and read level of mercury in L. (5) Open J and observe IPresented a t the meeting of the ChemicalInstitute of Canada
at Halifax, Nova Scotia, May 31, 1949. a M ~ T I ND. , R.,J. CEEM.EDUC.,21,383 (1944). a LONG, R. H., SchDol Sci. and Math., 46,423 (1946). ~HERRINC-TON, B. L., AND M. P. STARR, Ind. Eng. Chem., Anal. Ed., 14, 62 (1942). 325
