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Vapour pressure for all substances, Study notes of Mechanics of Pressure Vessels

The definition of vapour pressure,process and measurement

Typology: Study notes

2022/2023

Uploaded on 11/17/2023

nyangoma-caroline
nyangoma-caroline 🇬🇧

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VAPOUR PRESSURE
Is the pressure exerted by a vapor in thermodynamic equilibrium or it can also
be defined as the pressure exhibited by vapor present above a liquid surface
When two objects are in thermal dynamic, they are said to have the same
temperature. During the process of reaching thermal equilibrium, heat, which is
a form of energy, is transferred between objects. As the temperature of a liquid
increases the attractive interactions between liquid molecules become less
significant in comparison to the entropy of these molecules in the gas phase
increasing the vapor pressure thus liquids with strong intermolecular
interactions are likely to have smaller vapor pressure, with reserve true
It relates to the balance of particles escaping from a liquid or solid in equilibrium
with those coexisting vapor phase. A substance with high vapor pressure at
normal temperature is referred to as Volatile
Factors that influence vapor pressure
Temperature
Intermolecular forces of attraction
Increasing temperature causes more evaporation and increases the vapor
pressure because more liquid particles escape as gas
Intermolecular forces, Evaporation, Vapor Pressure and Boiling Point
Substances with strong intermolecular attractions will have low vapor
pressure due to low evaporation and high boiling point because a lot of energy is
needed to go from liquid to gas due to the strong attractions
Vapor Pressure and Boiling Point
Atmospheric pressure interferes with evaporation and thereby making it difficult
to boil thus therefore for a liquid to boil, vapor pressure of a liquid is equal to
the atmospheric pressure
Weak intermolecular attraction
Strong intermolecular attraction
Volatile liquids evaporate very easily
and have a high vapor pressure
Don’t evaporate easily and have low
vapor pressure
Have low boiling point
High boiling point
Bp ethanol
Bp water=°C
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VAPOUR PRESSURE

Is the pressure exerted by a vapor in thermodynamic equilibrium or it can also be defined as the pressure exhibited by vapor present above a liquid surface When two objects are in thermal dynamic, they are said to have the same temperature. During the process of reaching thermal equilibrium, heat, which is a form of energy, is transferred between objects. As the temperature of a liquid increases the attractive interactions between liquid molecules become less significant in comparison to the entropy of these molecules in the gas phase increasing the vapor pressure thus liquids with strong intermolecular interactions are likely to have smaller vapor pressure, with reserve true It relates to the balance of particles escaping from a liquid or solid in equilibrium with those coexisting vapor phase. A substance with high vapor pressure at normal temperature is referred to as Volatile Factors that influence vapor pressure

  • Temperature
  • Intermolecular forces of attraction Increasing temperature causes more evaporation and increases the vapor pressure because more liquid particles escape as gas Intermolecular forces, Evaporation, Vapor Pressure and Boiling Point Substances with strong intermolecular attractions will have low vapor pressure due to low evaporation and high boiling point because a lot of energy is needed to go from liquid to gas due to the strong attractions Vapor Pressure and Boiling Point Atmospheric pressure interferes with evaporation and thereby making it difficult to boil thus therefore for a liquid to boil, vapor pressure of a liquid is equal to the atmospheric pressure Weak intermolecular attraction Strong intermolecular attraction Volatile liquids evaporate very easily and have a high vapor pressure Don’t evaporate easily and have low vapor pressure Have low boiling point High boiling point Bp ethanol Bp water=°C

Vapor Pressure of a Substance Vapor pressure of any substance increases nonlinearly with temperature. At normal boiling point, vapor pressure equals the ambient atmospheric pressure with an increase in temperature, the vapor pressure becomes greater than atmospheric pressure and causes the liquid to form vapor bubbles Partial Pressure It refers to the vapor pressure that a single component in a mixture contributes to the total pressure Air at sea level, saturated with water vapor at 20°C has a partial pressure of about 23kPaof water ,78kPa of nitogen,21kPa of oxygen and 0.9kPa of argon ,totaling 102.2kPa,making the basis for standard atmosphere 23kPaof water ,78kPa of nitogen,21kPa of oxygen and 0.9kPa of argon ,totaling 102.2kPa,making the basis for standard atmospheric pressure