njit-etd1961-002 - New Jersey Institute of Technology

Prior to the present correlation of the thermodynamicproperties of formaldehyde, an extensive andthorough literature search was conducted. However,no correlation of the thermodynamic properties offormaldehyde was found and only limited data wereuncovered from which such a correlation could be constructed.The critical temperature and pressure were estimatedby Walker¹6 as 141 °C. and 65 atm. respectively.Using Lydersen's correlation8, ¹0, the author foundthe critical temperature, pressure, and volume to be141.33°C, 66,897 atm., and 113 cc/g-mole respectively,values which are in cic agreement with the findingsof Walker. eased on a survey of 67 compounds, theLydersen method has the following average accuracy¹0:For calculation of % errorTc 1.3Pc 4,5Vc 2-5The deviation was only 1,7% for the critical temperatureestimation of acetaldehyde by the method of Lydersen.The critical o compressibility factor was estimatedin the present stud) to be 0,222 which is less than thatof water, This value,. Is believed to be reasonably accurate,because th. dipo1 moment formaldehyde is greater thanthat of water.No vapor pressure date ,-)n formaldehyde above itsnormal boiling located; so the Riedelcorrelation¹¹ was used to estimate the vapor pressureover the temperature range of -10 ° C. to 141°C. TheRiedel method was chosen because it requires theminimum data of only critical temperature, criticalpressure, and one boiling point which were reasonably