Measured enthalpies for mixtures of benzene with n-pentane

Abstract

selected to facilitate comparison of the total fertilizer nutrient contents, N + PZO5, of the saturated solutions in the several systems.The 0°C isotherm of the multiphosphate system over the pH range studied comprises three branches representing solutions saturated, respectively, with (KH4)2HP04, (NH4)4PzO'i 9 HzO, and h H4H2P04, (NH4)3HP207. H 2 0 , (NH4)5P3010. 2H20, and ("4)6P4013.2H20.Only one invariant solution was determined. It was saturated with (NH4)2HP04, (NH4)3HPO?. H20, (NH4)4P207. HzO, (NH4)5P3O1o.2H2OJ and (NH4)d'4013. 2H20, and contained 12.61% N and 41.04% P z O~ distributed as ortho-21, pyro-35, tripoly-14, and tetrapolyphosphate 29%. It had a pH of 6.39, a value near that (6.50) of the invariant solution of the ternary system N H~H~P z O~-H Z O saturated with tri-and tetraammonium pyrophosphate and near that (6.44) of the invariant solution of the quaternary system NH3-H3P04-H4P207-H20 saturated with tri-and tetraammonium pyrophosphates and diammonium orthophosphate. A second invariant point, representing a solution saturated with XH4H2P04, (KHJzHP04, (NH4)3HP207.HzOJ (NH4)SP3010. H 2 0 , and (NH4)6P4013. 2H20, was estimated from plots of pH vs. N or P205 to contain lh.6% N and 44.2% PZOS and to have a pH of 5.9.As shown in Figure 1, the total fertilizer nutrient contents of the solutions saturated with ammonium ortho-, pyro-, tripoly-, and tetrapolyphosphates are significantly higher than those of solutions with the same ratio N:Pz05 that are saturated with only a single phosphate species. As shown in Figure 2, a t each ratio N : P 2 0 5 , a solution of the six-component system saturated with ammonium ortho-, pyro-, tripoly-, and tetrapolyphosphates has a nutrient content (h' + P205) 510%higher than that of a solution of the five-component system saturated with only ammonium ortho-, pyro-, and tripolyphosphates, and 10-25'% higher than that of a solution of the four-component system saturated with only ammonium orthoand pyrophosphates. The isotherms in Figure 2 will be useful in the preparation of ammonium polyphosphate solutions in the most desirable pH range with maximum fertilizer nutrient contents that will not salt out a t 0°C.A flow calorimeter was used to measure four compositions of benzene with n-pentane between 260' and 7OO0F, with pressures ranging up to 1400 psia.

Enthalpies of ternary system pentane-cyclohexane-benzene

“…The results of enthalpy measurements for the binary systems n-pentane-cyclohexane (8), n-pentane-benzene (7), and cyclohexane-benzene (6) have been published, but the enthalpy values for the ternary mixture of pentane-cyclohexane-benzene have not previously been reported. Three compositions of this ternary mixture of a paraffin, naphthalene, and aromatic have been studied, one rich in pentane, one an equimolar mixture, and the third, rich in benzene.…”

“…The details of this apparatus have been presented (9). Repeated studies (5, [7][8][9] performed by comparing the results with published values for n-pentane (2-4) and liquid water (11) have…”