The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor.
A liquid in a vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high-pressure has a higher boiling point than when that liquid is at atmospheric pressure. In other words, the boiling point of a liquid varies depending upon the surrounding environmental pressure. For a given pressure, different liquids boil at different temperatures.
The normal boiling point (also called the atmospheric boiling point or the atmospheric pressure boiling point) of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level, 1 atmosphere. At that temperature, the vapor pressure of the liquid becomes sufficient to overcome atmospheric pressure and allow bubbles of vapor to form inside the bulk of the liquid. The standard boiling point is now (as of 1982) defined by IUPAC as the temperature at which boiling occurs under a pressure of 1 bar.
The heat of vaporization is the energy required to transform a given quantity (a mol, kg, pound, etc.) of a substance from a liquid into a gas at a given pressure (often atmospheric pressure).
Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation. Evaporation is a surface phenomenon in which molecules located near the liquid's edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, resulting in the formation of vapor bubbles within the liquid.
Read more about Boiling Point: Saturation Temperature and Pressure, Relation Between The Normal Boiling Point and The Vapor Pressure of Liquids, Properties of The Elements, Boiling Point As A Reference Property of A Pure Compound, Impurities and Mixtures
Other articles related to "boiling point, point, boiling, boiling points":
... At a temperature below the boiling point, any matter in liquid form will evaporate until the condensation of gas above reach an equilibrium ... At this point the gas will condense at the same rate as the liquid evaporates ... A liquid at its boiling point will evaporate more quickly than the gas can condense at the current pressure ...
... water under pressure at temperatures between the usual boiling point, 100 °C (212 °F) and the critical temperature, 374 °C (705 °F) ... or "pressurized hot water." Superheated water is stable because of overpressure that raises the boiling point, or by heating it in a sealed vessel with a ... to refer to water at atmospheric pressure above its normal boiling point, which has not boiled due to a lack of nucleation sites (sometimes experienced by heating liquids in a ...
... Boiling – the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the ... cooking technique which food substance, usually a vegetable or fruit, is plunged into boiling water, removed after a brief, timed interval, and finally plunged into ... liquid in the pot to rise to a higher temperature before boiling ...
... Stronger inter-molecular van der Waals forces give rise to greater boiling points of silanes ... As the boiling point of silanes is primarily determined by weight, it should not be a surprise that the boiling point has almost a linear relationship with the size (molec ... A straight-chain silane will have a boiling point higher than a branched-chain silane due to the greater surface area in contact, thus the greater van der Waals forces, between adjacent molecules ...
... In the preceding section, boiling points of pure compounds were covered ... Vapor pressures and boiling points of substances can be affected by the presence of dissolved impurities (solutes) or other miscible compounds, the degree of effect depending on the concentration of ... the solution's volatility, and thus raises the normal boiling point in proportion to the concentration of the solutes ...
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