\nIn my previous post<\/a> I mention Gibbs free energy and how it can be used to predict spontaneity. Specifically, if Gibbs free energy decreases from a process, said process is predicted to be spontaneous.<\/p>\n\n \nClothes drying on a clothesline in winter can serve as as interesting illustration of Gibbs free energy. Although drying clothes is a physical change, not chemical, it can still serve as a case for the Gibbs free energy model.<\/p>\n \nThe theory is that, even when the outdoor temp remains below zero Celsius, negative 5°C, for instance, laundered clothes hung outdoors to dry will eventually do so. They will even freeze first, perhaps, but then be dry at some point afterwards.<\/p>\n \nGibbs free energy can predict that said drying process can work, as follows:<\/p>\n \nG=H-TS, for a change, becomes ΔG=ΔH-TΔS<\/p>\n \n(See my previous post<\/a> for the definitions of parameters.)\n<\/p>\n \nIntuitively, people realize that, for said process to work, the enthalpy (H) actually has to increase. Since enthalpy is related to heat, it seems hard to imagine, at -5°C, how it can.<\/p>\n \nYet, even under such conditions, there is enough environmental energy (from sunlight, for instance) to raise the enthalpy of a water molecule here and there. Importantly, the increase of entropy (disorder) from being frozen in ice to a free-moving vapour molecule is significant.<\/p>\n \nIn ΔG=ΔH-TΔS, T is absolute temperature. Therefore, at -5°C, T is 268K.<\/p>\n \nNote that in a closed system, where heat cannot enter, such process likely wouldn’t work. Yet, with an open system, such as outdoors in winter, heat energy is always capable of arriving or leaving.<\/p>\n \nSource:<\/p>\n “Saturated Ice and Steam – Thermodynamic Properties.” The Engineering ToolBox. https:\/\/www.engineeringtoolbox.com\/saturated-ice-steam-d_970.html<\/a>\n \nWhite, J.E. (1987). Physical Chemistry.<\/em> Books for Professionals, Inc.<\/p>\nJack of Oracle Tutoring by Jack and Diane,<\/a> Campbell River, BC.\n \n\n","protected":false},"excerpt":{"rendered":" Tutoring chemistry, interesting applications can come up. The tutor mentions one connected with Gibbs free energy. In my previous post I mention Gibbs free energy and how it can be used to predict spontaneity. Specifically, if Gibbs free energy decreases …<\/p>\n