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Correlating vapor pressures and heats of solution for the ammonium nitrate—water system: An enthalpy–concentration diagram
Author(s) -
Othmer Donald F.,
Frohlich Gerhard J.
Publication year - 1960
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690060210
Subject(s) - chemistry , thermodynamics , enthalpy , ammonium nitrate , vapor pressure , enthalpy change of solution , aqueous solution , logarithm , ammonium , chart , organic chemistry , mathematics , physics , statistics , mathematical analysis
The usual tedious method of construction of enthalpy‐concentration charts for solutions of solids requires data seldom available. A new, simple method is therefore presented that utilizes more readily available data, that is vapor pressures of the solutions. These plot as straight lines on a logarithmic‐reference substance plot. Differences from unity of the slopes of these lines represent heats of solution, and when this difference function is integrated between concentration limits the integral heat of solution is obtained. The enthalpy chart is then readily constructed by use of the specific heats of liquid and solid. Ammonium nitrate is the solid used in this example, and water is the liquid because of the industrial importance of aqueous solutions. Vapor pressures were carefully determined experimentally, and the enthalpy chart was developed from the straight lines of the logarithmic plot and available heat data. Constants for the vapor‐pressure curves for ammonium nitrate solutions and equations for enthalpies of solid ammonium nitrate are given for the temperature range 0° to 170°C.