What is Boiling Point?
Boiling point is usually defined as the temperature with which an element or a substance (specifically liquids) comes to a boil. Scientifically, it is defined as temperature at which a liquid’s vapor pressure is on par with the environmental pressure surrounding it.
A liquid has a low boiling point when contained in an environment that is vacuumed compared to a liquid at atmospheric pressure. On the other hand, in high pressure environment, a liquid has higher boiling point than in atmospheric pressure. This shows that a liquid’s boiling point varies and depends on the pressure of the surrounding environment. Therefore, various liquids at varied pressure will boil at various temperatures.
Atmospheric boiling point is considered as the normal boiling point for a given liquid. This means that a vapor pressure must be equivalent to the sea level atmospheric pressure. The normal boiling point is the temperature at which the liquid’s vapor pressure overcomes the atmospheric pressure. This is characterized by bubbles formed in the liquid. This means that the liquid has overcome the atmospheric pressure by lifting the liquid in the form of bubbles. As of the year 1982 and until now, the accepted boiling point as defined by IUPAC is the temperature under the atmospheric pressure at sea level.
Boiling point is responsible for the vaporization of liquids. However, it is not necessary for a liquid to reach its boiling point to vaporize. Evaporation occurs even at a temperature below a liquid’s boiling point. Evaporation is a process when a liquid’s molecule escapes its surrounding in a form of air molecule. However, boiling is also a process when liquid molecules escape forming bubbles and evaporate.
On the other hand, there is another term for a liquid that turns to vapor even with the slightest thermal energy ‘“ saturated liquid. On the contrary, a saturated vapor can prevent itself from condensing even if it contains the least thermal energy. Boiling point can also be referred to as saturation temperature. The temperature that corresponds to saturation pressure that causes a liquid to boil into vapor phase is called saturation temperature.
With the explanation about saturation temperature, it can be said that a liquid can be saturated with thermal energy. Accumulation or increase in thermal energy will cause a phase transition.
Isobaric is a term used when pressure remains constant within a system. When this happens, a vapor will commence condensation even at saturation temperature. This will turn the vapor back to its liquid form due to the removal of thermal energy. This transition conversely happens when more thermal energy is utilized. When this happens liquid will boil into its vapor phase at saturation temperature and pressure.
Boiling point is also associated to a term saturation pressure. This pressure corresponds to saturation temperature that causes a liquid to boil into vapor phase. Saturation pressure and temperature are directly related where one pressure increases so is the temperature.
Same principle applies with saturation pressure. In an isothermal system, vapor at both saturation temperature and pressure will commence to turn back into its condensed phase as more pressure is applied to the system.