The Rates of Evaporation and the Vapor Pressures of Tungsten, Molybdenum, Platinum, Nickel, Iron, Copper and Silver

Abstract

Langmuir and Mackay's data on the rates of evaporation of tungsten, molybdenum and platinum have been corrected to the tungsten temperature scale of Forsythe and Worthing. Similar data on nickel, iron, copper and silver are published for the first time on the same temperature scale. The third law of thermodynamics has been assumed in all calculations and the vapor pressures are calculated from the rates of evaporation. The experimental data check the third law as shown by the constancy of the calculated values of X 0 , the latent heat of evaporation at the absolute zero. Tables are given of the rates of evaporation and the vapor pressures up to the boiling points. The data are compared with those of other investigators. The evaporation of metals heated in an atomic hydrogen flame was very rapid and gave results which confirmed the data on evaporation in vacuum. The values of X D expressed in cal. gm. (atom) -1 and the boiling points in degrees Kelvin are W Mo

Vapor pressures and standard molar enthalpies, entropies and Gibbs energies of sublimation of three 4-substituted acetanilide derivatives

“…, M is the molar mass of the compound, is the vaporization constant, which is equal to unity only for experiments in vacuo [18], S (in m 2 ) is the surface of the sample considered equal to the area of the bottom of the crucible, R is the gas constant (in J mol −1 K −1 ), k cal = ( √ 2 · · R)/˛ is the instrumental constant. The consistency of the vapor pressure results above the liquid (melted) substance measured by a thermobalance subjected to isothermal and nonisothermal conditions under a flowing inert gas atmosphere was tested in our previous vaporization studies on pesticides using recommended reference compounds (i.e., benzoic acid [4,11], succinic acid and salicylic acid [4], acetanilide [5] and ferrocene [7]).…”

A Study of the Thermodynamic Properties of the Vanadium-Iron Alloy System

“…(26,(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55) A graphical comparison of the results of these studies with a plot of the vapor pressure equation derived in the present work is made in Figure 19. The first significant determination of the vapor pressure of iron was made by Langmuir et aL.v"*^' who measured the rate of evaporation of an iron filament of unreported purity in the temperature range frona 1270 to 1580''K.…”

“…An estimate of these errors is ^0.5 cal/ (gm-atona)(deg)for the integral entropies and iSOO cal/gm-atom for the integral enthalpies. 45 …”

Effect of Sintering Time on the Densification, Microstructure, Weight Loss and Tensile Properties of a Powder Metallurgical Fe-Mn-Si Alloy

“…The sublimation rate of a certain component in the bulk materials can be determined by the Langmuir theory, which is given as [38][39][40]:…”