how are VAPOR PRESSURE and ATMOSPHERIC PRESSURE related ?

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  • 1 decade ago
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    Atmospheric Pressure= Pressure applied by air column.

    Vapor pressure:

    As with water, all liquids tend to evaporate at any given temperature, may be below it's boiling point- some molecules tend to garner energy from other molecules and tend to escape the liquid mass and evaporate, exertingan upward pressure. Usually this energy ( upward pressure) is balanced with Atmospheric pressure and is characteristic of every liquid. This value is known as vapor pressure of 'the' liquid at that temperature and pressure and is generally mentioned at STP (Standard temperature and pressure)

    In general, the vapor pressure of a liquid changes inversely (I dontremember theexact formula- it's slightly different) with the ambient/ atmospheric pressure.So that with a decrease in ambient pressure the liquid's tendancy to evaporate increases ie boiling point is reduced while with an increasein ambient pressure, the boiling temperature increases. So much so thatucan have liquid water at 350 deg C athigh pressures (remember high pressure boilers?)

    or steam at 10 deg C at low ambient pressure (near vacuum)

  • 1 decade ago

    Vapors are released by anything that can burn, just by them sitting there. For example, you're releasing vapors right now. But the pressure isn't significant. Now, vapor pressure is generally thought of going up, while atmospheric pressure is thought of going down (even though it's all around us). When vapor pressure meets atmospheric pressure, boiling occurs (when you heat something on the stove, you're changing the vapor pressure). OR if atmospheric pressure meets vapor pressure, boiling occurs also. So if you leave a liquid to room temp., it's releasing vapors. When you heat it up, it released vapors more quickly, increasing it's vapor pressure.

    Source(s): physics class
  • 1 decade ago

    Atmospheric pressure is direct result of the weight of a column of air from sea-level to the edge of the troposphere (approximately, as the atmosphere has no defining boundary...it just gets progressively thinner).

    This is a baseline for measuring vapor pressures.

    Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. Vapor pressure changes with temperature...meaning with the right pressure applied (with respect to atmospheric pressure), you can have liquid water at 500 degrees F. Conversely, with an appropriate vaccum (below atmospheric pressure), cold water can boil.

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