(58j) New Method to Estimate the Sublimation Pressure for Solids

The sublimation pressure for solids is difficult to estimate mainly because of its small magnitude. In this research, a method to calculate sublimation pressure was developed. It was then used to estimate Antoine's constants for the substances studied. In the proposed method, experimental or estimated vapor-pressure data of the liquid phase are used as a basis to pinpoint the triple point and then the sublimation line is drawn from there in a van't Hoff plot with a slope estimated from the vapor-pressure line slope in the same plot. If vapor pressure data are not available, they can be estimated with the Gomez-Thodos generalized equation for vapor pressure. Three substances were used to test the proposed method: naphthalene, acetic acid, and hydrocyanic acid. In the tests, experimental and estimated values were compared. The results of these comparisons reflect that the method can be trustful in the estimation of the sublimation pressure and of Antoine's constants.