Practice of Kinetics (Comprehensive Chemical Kinetics, Volume 1)

270 EXPERIMENTAL MET HODS FOR HE TER o GE NE ou s RE ACT 10 NSThese methods are discussed briefly; further information is obtainable from thereferences already mentioned‘. 356- ”’.Surface viscosity can be measured with a canal viscometer or with a torsionviscometer. The former instrument measures the flow of the film through a slit ina barrier on a film balance; the latter, the damping caused by the presence of afilm on a body moving in the surface of the liquid. Interpretation of measurementson films with a constant viscosity is difficult and would be more so in the presenceof viscosity changes caused by reaction.Optical spectroscopy can be used, but usually requires a multiple reflectiontechnique because of the limited adsorption by a monomolecular film. A discussionof the advantages and limitations of the multiple reflection technique has beengiven by Harri~k’~’. Radioactive tracers can be used to study reaction in monomolecularfilms, the advantages and limitations are similar to those found in othertypes of heterogeneous reaction. In principle, it is possible to scan very small areasof film.For elements which emit weak P-particles, such as 14C or 35S, the rate ofdisappearance from the surface to the subphase can be studied because the rangeof radiation is only about 0.3 mm in water. However, back scattering occurs fromthe substrate which complicates theinterpretation. Thework by Masonet al. 379-381on the exchange of iodide ion in solution with a surface monolayer of asodostearicacid illustrates the difficulties of the technique.REFERENCES1 A. W. ADAMSON, Physical Chemistry of Surfaces, Interscience, New York, 1960, p. 457.2 D. 0. HAYWARD AND B. M. W. TRAPNELL, Chemisorption, Butterworths, London, 1964.3 G. C. BOND, Catalysis by Metnls, Academic Press, London, 1962, p. 49.4 P. H. EMMETT, Catalysis, Reinhold, New York, 1 (1954) 31.5 C. ORR, JR. AND J. M. DALLEVALLE, Fine Particle Measurement, Macmillan, New York, 1962.6 D. M. YOUNG AND A. D. CROWELL, Physical Adsorption of Gases, Butterworths, London,1962.7 H. S. TAYLOR, Discussions Faraday SOC., 8 (1950) 8.8 W. G. FRANKENBURG, J. Am. Chem. SOC., 66 (1944) 1827.9 A. COUPER AND D. D. ELEY, Discussions Faraday Soc., 8 (1950) 172.10 R. RUDHAM AND F. S. STONE, Trans. Faraday Soc., 54 (1958) 420.11 J. A. BECKER, E. J. BECKER AND R. G. BRANDES, J. Appl. Phys., 32 (1961) 411.12 R. W. ROBERTS, Brit. J. Appl. Phys., 14 (1963) 537.13 I. LANGMUIR AND D. S. VILLARS, J. Am. Chem. SOC., 53 (1931) 486.14 3. K. ROBERTS, Proc. Roy. SOC. (London), A, 152 (1935) 445, 464.15 H. D. HAGSTRUM, Phys. Reo., 96 (1954) 336.16 R. GOMER, J. Chem. Phys., 21 (1953) 293.17 R. H. GOOD AND E. W. MULLER, Handbook ofPhysics, Springer-Verlag, Berlin, 21 (1956) 176.18 F. G. ALLEN, J. EISINGER, H. D. HAGSTRUM AND J. T. LAW, J. Appl. Phys., 30 (1959) 1563.19 H. D. HAGSTRUM, J. Appl. Phys., 32 (1961) 1020.20 J. T. LAW, J. Phys. Chem., 59 (1955) 543.21 R. B. ANDERSON AND P. H. EMMETT, J. Phys. Chem., 55 (1951) 337.22 H. D. HAGSTRUM AND C. D’AMICO, J. Appl. Phys., 31 (1960) 715.23 H. E. FARNSWORTH AND R. F. WOODCOCK, Advances in Catalysis, 9 (1957) 123.