The Vapor Pressure, Orthobaric Liquid Density, and Critical Constants of Isobutane

摘要

The vapor pressures and orthobaric liquid densities of isobutane (propaneminus;2hyphen;methyl) were measured from 30deg; to 125deg;C. The equationlog10pthinsp;lpar;normal atmos.rpar;equals;4.31269ndash;1126.71sol;Tthinsp;thinsp;lpar;Tequals;tcompfn;Cthinsp;lpar;Int.rpar;plus;273.13rpar;gives a fair representation of the vapor pressures.The critical constants of isobutane are determined by the compressibility method. They are:tc=134.98plusmn;0.05deg;C (Int.),pc=36.00plusmn;0.05 normal atmos.,vc=0.263 liters per mole (4.53 ml per g),dc=3.80 moles per liter (0.221 g per ml). The uncertainty in the critical volume and density is 2 percent.