natural gas plus 0%, 5.5%, and 10.0% water in the sour natural gas. The uncertainty bands reflect three standard deviations as provided by the maximum likelihood computer program. They do not contain the unknown systematic errors. While the usual experimental diagnostics for adsorption were absent, the adsorption of one molecule out of 1000 causes about ±0.3 cm3/mol in Sm and ±75 cm6/mol2 in Cm. The usual effect of adsorption is to make the computed Bm too negative with Cm too positive for compensation. ConclusionsPVT data plus second and third virial coefficients have been reported for six wet natural gas mixtures. The presence of small amounts of water is seen to have a major influence on the densities, Bm and, particularly, Cm.It has been shown elsewhere (7) that Bm and Cm for the sweet natural gas mixtures to 5.0% water content are predicted within experimental uncertainties by the correlations of Tsonopoulos ( 8) and Orbey and Vera (9), respectively. The prediction Is a priori in that the binary Interaction constants k,¡ contained in both correlations were not adjusted to fit the data but rather the values used were those of Prausnitz (10). The 10.0% water/sweet gas virial coefficients are not so well predicted possibly due to poor values of B, and C," for pure water. These correlations generally predict reasonable values of B,i and Cl/k as long as no more than one polar molecule is involved in the interaction. Thus, a priori prediction of Bm and Cm for any of the sour gas systems is poor due to the presence of C02, H2S, and, in the last two systems, water.

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