The Collaborative International Dictionary
Vapor pressure \Vapor pressure\ or Vapor tension \Vapor tension\ . (Physics) The pressure or tension of a confined body of vapor of a chemical substance in equilibrium with the solid or liquid form of the substance. The pressure of a given saturated vapor is a function of the temperature only, and may be measured by introducing a small quantity of the substance into a barometer and noting the depression of the column of mercury.
Wiktionary
n. (context physics English) The pressure that a vapor exerts, or the partial pressure if it is mixed with other gases.
WordNet
n. the pressure exerted by a vapor; often understood to mean saturated vapor pressure (the vapor pressure of a vapor in contact with its liquid form) [syn: vapour pressure]
Wikipedia
Vapor pressure or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's evaporation rate. It relates to the tendency of particles to escape from the liquid (or a solid). A substance with a high vapor pressure at normal temperatures is often referred to as volatile. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the kinetic energy of its molecules also increases. As the kinetic energy of the molecules increases, the number of molecules transitioning into a vapor also increases, thereby increasing the vapor pressure.
The vapor pressure of any substance increases non-linearly with temperature according to the Clausius–Clapeyron relation. The atmospheric pressure boiling point of a liquid (also known as the normal boiling point) is the temperature at which the vapor pressure equals the ambient atmospheric pressure. With any incremental increase in that temperature, the vapor pressure becomes sufficient to overcome atmospheric pressure and lift the liquid to form vapor bubbles inside the bulk of the substance. Bubble formation deeper in the liquid requires a higher pressure, and therefore higher temperature, because the fluid pressure increases above the atmospheric pressure as the depth increases.
The vapor pressure that a single component in a mixture contributes to the total pressure in the system is called partial pressure. For example, air at sea level, and saturated with water vapor at 20 °C, has partial pressures of about 2.3 kPa of water, 78 kPa of nitrogen, 21 kPa of oxygen and 0.9 kPa of argon, totaling 102.2 kPa, making the basis for standard atmospheric pressure.
Usage examples of "vapor pressure".
He bled hydrogen gas slowly through the valve, lowering the fuel's vapor pressure without letting fuel boil out the valve itself.
The external forces acting on it--the currents, the ocean waves, the salinity of the water and its resultant density, tides, the Coriolis effect, the strains on the tugboat lines, winds, rainfall, vapor pressure, atmospheric pressure, propeller vibration, the heat of the sun--dozens of factors--are even more complex.
A fluid boils when its vapor pressure equals the pressure of the surrounding gases.
To make the bubbles form, you can heat up the fluid and increase its vapor pressure.
And the membrane was going to burst from sheer vapor pressure in the next ten minutes anyway.
Most of it had long ago escaped into space or frozen on Darkside, but now vapor pressure had struck a balance, and there was some carbon dioxide, nitrogen, ammonia, and inert gas free.
If it had a high vapor pressure there would be a purging job on top of the pumping one no, not necessarily, come to think of it.
When removed from the freezer, the butane will naturally warm to ambient temperature but will remain a liquid in the tank due to vapor pressure.
The perihelion temperature on Ganymede never rises high enough to melt the ice of Neptune's Trident, but it does lift through the few niggardly degrees necessary to make the vapor pressure of Ice III known in Ganymede's air.
He began slowly to smile, as the discrete fragments of an idea began to sort themselves out and fit properly together in his mind--an idea that involved the vapor pressure of metallic blood, the leaking qualities of the utility suits worn by his erstwhile assistants, and the bloodthirstiness of his many-legged acquaintances of the day.