DEPENDENCE OF THE THERMODYNAMIC PROPERTIES OF N-ALKYLKETONES ON THE FLASH POINT

Abstract

The number of organic compounds has exceeded 40 million and increases by 300 thousand each year. In order to perform technological calculations of the production process, storage and transportation of materials we need the know the thermodynamic properties and the rate of fi re and explosion hazard of the substances used. It is, therefore, important to develop methods of forecasting fi re danger indicators and thermodynamic properties of substances, based on a minimal amount of experimental data. To solve this problem it is necessary to determine the relationship between the molecular characteristics and thermodynamic properties of substances in homologous series. The objects of the present study are substances of n-alkylketones homologous series. We have measured the saturation vapour pressure and the density of liquid substances in the series at various temperatures. Using the experimental data and the ideal gas parameters (standard liquid volume and temperature) we calculated the inner energy, the entropy, and the Helmholtz energy. The analysis proved that values of the thermodynamic functions of substances additively depend on the molar weight of n-alkylketones in the homologous series. Existing literature on the problem also demonstrates that similar dependence is observed for the fl ash point of n-alkylketones. Taking into account the fact that the named properties generally tend to change, we can establish a linear correlation between the fl ash point values and the Helmholtz energy of the substances in the homologous series. The corresponding equations were obtained. The established regularities and equations based on them, allow us to forecast the properties of homologous series of substances with enough accuracy for practical applications.

Keywords

• n-alkylketones
• liquid-vapor equilibrium
• Helmholtz energy
• internal energy
• entropy; fl ash point
• state equation.