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Topic: Vapor pressure


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  Vapor Pressure
The temperature at which the vapor pressure is equal to the atmospheric pressure is called the boiling point.
The pressure of this equilibrium is called the saturation vapor pressure.
The boiling point is defined as the temperature at which the saturated vapor pressure of a liquid is equal to the surrounding atmospheric pressure.
hyperphysics.phy-astr.gsu.edu /hbase/kinetic/vappre.html   (610 words)

  
  Vapor pressure - Wikipedia, the free encyclopedia
Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases.
This is the equilibrium vapor pressure or saturation vapor pressure of that substance at that temperature.
It may be noted that the vapor pressure of a substance in liquid form is usually different from the vapor pressure of the same substance in solid form.
en.wikipedia.org /wiki/Vapor_pressure   (593 words)

  
 Saturation vapor pressure - Wikipedia, the free encyclopedia
The saturation vapor pressure is the static pressure of a vapor when the vapor phase of some material is in equilibrium with the liquid phase of that same material.
It is the vapor pressure usually found over liquid water, and is a dynamic equilibrium where the rate of condensation of water equals the rate of evaporation of water.
Thus, at saturation vapor pressure, air has a relative humidity of 100% and condensation occurs with any increase of water vapor content or a reduction in temperature.
en.wikipedia.org /wiki/Saturation_vapor_pressure   (384 words)

  
 AllRefer.com - vapor pressure (Chemistry) - Encyclopedia   (Site not responding. Last check: 2007-11-02)
vapor pressure, pressure exerted by a vapor that is in equilibrium with its liquid.
Vapor pressure depends on various factors, the most important of which is the nature of the liquid.
Another factor affecting vapor pressure is the presence of dissolved substances in the liquid or solid; according to Raoult's law, the vapor pressure of a pure liquid or solid is lowered by the addition of a solute.
reference.allrefer.com /encyclopedia/V/vaporpre.html   (416 words)

  
 Vapor Pressure
Vapor pressure is defined as the pressure of the vapor of a liquid or solid in equilibrium with the liquid or solid state.
The Vapor Pressure of a liquid at a given temperature is a characteristic property of that liquid.
Vapor pressure of a liquid is intimately connected to another physical property known as boiling point, but that will be another topic for discussion.
members.aol.com /profchm/vp.html   (703 words)

  
 Phase Changes: Vapor Pressure   (Site not responding. Last check: 2007-11-02)
The vapor pressure is literally the partial pressure of the compound in the gas.
As these equations illustrate, experiment data for the vapor pressure of a liquid as a function of temperature enables the calculation of both the normal boiling point (or indeed any boiling point), the standard enthalpy of vaporization, and the standard entropy of vaporization.
Thus the pressure measured by the manometer is attributable solely to the enthanol vapor.
www.chm.davidson.edu /ChemistryApplets/PhaseChanges/VaporPressure.html   (603 words)

  
 The MSDS HyperGlossary: Vapor Pressure
The vapor pressure of a liquid is the pressure exerted by its vapor when the liquid and vapor are in dynamic equilibrium.
The boiling point is the temperature at which the vapor pressure of the liquid equals the external pressure.
The vapor pressure of mixtures is dealt with using Raoult's Law.
www.ilpi.com /msds/ref/vaporpressure.html   (649 words)

  
 ISA | Getting a grip on humidity
If we consider air, this means the total atmospheric pressure of 1.013 bars (14.7 pounds per square inch absolute) is the sum of the partial pressures of all its constituents: nitrogen, oxygen, water vapor, argon, carbon dioxide, and various other gases in trace amounts.
If saturation vapor pressure has occurred in air or a gas mixture, introducing additional water vapor requires that an equal amount of water vapor condense out of the mixture as a liquid or solid.
Vapor pressure tables also enable one to look up the saturation vapor pressure for any temperature, and of course there are a number of water vapor calculation programs available for PCs.
www.isa.org /InTechTemplate.cfm?Section=Departments4&template=/ContentManagement/ContentDisplay.cfm&ContentID=16795   (1008 words)

  
 Vapor Pressure
The vapor pressure of a liquid is the equilibrium pressure of a vapor above its liquid (or solid); that is, the pressure of the vapor resulting from evaporation of a liquid (or solid) above a sample of the liquid (or solid) in a closed container.
Conversely, vapor pressure decreases as the temperature decreases.
The pressure exerted by the gas in equilibrium with a solid or liquid in a closed container at a given temperature is called the vapor pressure.
www.chem.purdue.edu /gchelp/liquids/vpress.html   (447 words)

  
 Water Vapor and Vapor Pressure
The boiling point is defined as the temperature at which the saturated vapor pressure of a liquid is equal to the surrounding atmospheric pressure.
Since the vapor pressure increases with temperature, it follows that for pressure greater than 760 mmHg (e.g., in a pressure cooker), the boiling point is above 100C and for pressure less than 760 mmHg (e.g., at altitudes above sea level), the boiling point will be lower than 100C.
Values were taken from the saturated vapor pressure table for water near 100 degrees C. An empirical fit to these data values was made, and the formula obtained is shown on the diagram.
www.vivoscuola.it /us/rsigpp3202/umidita/copie/watvap.htm   (360 words)

  
 Vapor Pressure: Molecular Size
The measurement of pressure exerted by a vapor is demonstrated using barometers.
Vapor pressure varies with the strength of the intermolecular forces in the liquid.
Methanol has the higher vapor pressure because its molecules are smaller than those of ethanol, and so its intermolecular forces are less than ethanol's.
jchemed.chem.wisc.edu /JCESoft/CCA/CCA2/MAIN/VAPORES5/CD2R1.HTM   (464 words)

  
 Gas Laws: Pressure   (Site not responding. Last check: 2007-11-02)
Pressure (P) is the ratio of the force (F) applied to a surface to the surface area (A).
A pressure of 1 torr or 1 mm Hg is literally the pressure that produces a 1 mm difference in the heights of the two columns of mercury in a manometer.
The vapor pressure of water is 23.8 torr at 25
www.chm.davidson.edu /ChemistryApplets/GasLaws/Pressure.html   (1064 words)

  
 Kids.net.au - Encyclopedia Vapor pressure -   (Site not responding. Last check: 2007-11-02)
This is termed the vapor pressure of that substance at that temperature.
When the ambient pressure equals the vapor pressure of any liquid, the liquid and vapor are in equilibrium.
Thus, at any given pressure, the boiling point of a substance is the temperature at which the vapor pressure of the substance in liquid form equals the ambient pressure.
www.kidsseek.com /encyclopedia-wiki/va/Vapour_pressure   (348 words)

  
 Vapor Pressure and Humidity   (Site not responding. Last check: 2007-11-02)
The pressure exerted by the air is actually the sum of the partial pressures exerted by the gaseous components of air, including water vapor.
Thus, the vapor pressure is a good indicator of the number of vapor molecules in the air.
The vapor pressure at which this occurs is the saturation vapor pressure.
www.cimms.ou.edu /~cortinas/1014/l11_3.html   (307 words)

  
 vapor pressure. The New Dictionary of Cultural Literacy, Third Edition. 2002
In physics and chemistry, the atmospheric pressure that would be exerted by any single component of a gas if that component were the only one present.
For example, the vapor pressure of oxygen in the atmosphere of the Earth is the pressure that would exist if everything but oxygen were removed.
The total atmospheric pressure is the sum of the vapor pressures of all the materials in the atmosphere.
www.bartleby.com /59/19/vaporpressur.html   (164 words)

  
 Vapor Pressure
At this point, the vapor pressure of the liquid is equal to the partial pressure of its vapor in the flask.
Round pressure to the nearest 1 mm Hg and temperature to the nearest 0.1°C. Open the side valve of the pressure sensor so the test tube is open to the atmosphere.
To obtain the vapor pressure of methanol and ethanol, the air pressure must be subtracted from each of the measured pressure values.
dwb.unl.edu /calculators/activities/VaporPressure.html   (1979 words)

  
 USATODAY.com   (Site not responding. Last check: 2007-11-02)
Humidity is a measure of the amount of water vapor in the air, not the total amount of vapor and liquid.
One way is to divide the actual vapor pressure by the saturation vapor pressure and then multiply by 100 to convert to a percent.
Saturation of air: The condition under which the amount of water vapor in the air is the maximum possible at the existing temperature and pressure.
www.usatoday.com /weather/whumdef.htm   (1114 words)

  
 Pressure   (Site not responding. Last check: 2007-11-02)
The pressure of a gas arises from the collision of the gas particles (atoms or molecules) with the walls of the container.
If pressure arises from the collisions of particles with the sides of a container, it is reasonable that the more particles striking the wall in some period of time the higher the pressure.
The pressure exerted by the column of mercury is identical to that being exerted by the atmosphere.
neon.chem.uidaho.edu /~honors/pressure.html   (1463 words)

  
 Problem 1 - Vapor Pressure and Heat of Vaporization of Liquids
Vapor pressure is a fundamental thermodynamic property of a solid or liquid.
The vapor pressure is also an important parameter in evaluating environmental and safety hazards of chemicals (e.g., evaporation rate, persistence in the soil, flash point, emissions, etc.) [2].
Computing vapor pressures at any set of temperatures, using a vapor pressure equation (such as those described in the Introduction) to fit the simulation data, and then calculating answers at the Contest state points is a permitted strategy.
www.cstl.nist.gov /FluidSimulationChallenge/problems/problem1.htm   (1356 words)

  
 Water Vapor Pressure Effect
Water vapor pressure is the pressure exerted by water on the ambient air as it tries to evaporate.
Vapor pressure increases the volume being measured by increasing the contained volume and accelerating the speed of the bubble.
For example, At 22 degrees C, the vapor pressure of water is 19.827.
www.biosint.com /faqs/vapor.htm   (151 words)

  
 University Chemistry: Gases, The Empirical Gas Laws: Vapor Pressure
This is a pressure of the substance in the gas phase which is established at a particular temperature.
At room temperature the vapor pressure of ethanol is much higher, and the vapor pressure of mercury or potassium chloride is much lower, than is the vapor pressure of water.
partial pressure of the collected gas and the partial pressure of the gas phase of the liquid, which is its vapor pressure.
www.psigate.ac.uk /newsite/reference/plambeck/chem2/p01045.htm   (513 words)

  
 WXWISE Definitions   (Site not responding. Last check: 2007-11-02)
Evaporative Cooling: Energy is required to change the phase of water from a liquid to a vapor, which results in a cooling of the surrounding environment.
The average sea level pressure is approximately 1013 mb, or 29.92 inches of mercury.
Vapor Pressure: The partial pressure exerted by water vapor.
cimss.ssec.wisc.edu /wxwise/defintn.html   (531 words)

  
 Vapor Pressure   (Site not responding. Last check: 2007-11-02)
The presence of the solute in the water reduces the water's vapor pressure; the boiling temperature will then be the temperature at which the vapor pressure is 1 atm.
If the solution is "ideal", which salt / water is not, the vapor pressure of the solution,p, is related to the vapor pressure of the pure solvent,p', by the mole fraction of the solvent, x'.
The bottom line is: the vapor pressure of the solution is lowered from that of the pure solvent since x' is less than unity.
www.newton.dep.anl.gov /askasci/chem00/chem00233.htm   (465 words)

  
 Vapor Pressure: Using Barometers
The vapor pressures of water and ethanol are compared.
Pressure exerted by a vapor can be measured using barometers.
(The difference in the height of the mercury column before and after injecting the liquid is the vapor pressure of the liquid.) The vapor pressure of water is 20 millimeters of mercury.
jchemed.chem.wisc.edu /JCESoft/CCA/CCA2/MAIN/VAPORES1/CD2R1.HTM   (338 words)

  
 Vapor Pressure   (Site not responding. Last check: 2007-11-02)
This pressure is the vapor pressure of the substance at that temperature.
The vapor pressure of a substance increases with temperature.
For this reason, the line in the phase diagram which describes the vapor pressure undergoes a change of slope at the point where the substance freezes (called the triple point because all three phases –; liquid, solid, and gas – coexist at a single value of temperature and pressure).
chemlabs.uoregon.edu /Classes/jlong/CH238/vp.html   (2313 words)

  
 Vapor Pressure Measurement   (Site not responding. Last check: 2007-11-02)
Vapor pressure is a measure of the number of molecules which are present in the volume above a solid or liquid at equilibrium.
The vapor pressure of material in a vacuum system will seriously affect the operation of the system if the pressure is significant when compared to the desired base pressure of the system.
Below illustrates the rise of vapor pressure (gas) of frozen water under vacuum.
www.nexvac.com /tech_info/vac_fund_101/vapor_press.htm   (147 words)

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