Estimate Mass H2O Vapor in 1 m^3 Air at +20°C

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SUMMARY

The discussion focuses on estimating the mass of water vapor in 1 m³ of saturated air at +20°C. The saturation pressure for water vapor at this temperature is utilized alongside the ideal gas law to derive the mass of water vapor using the formula m_{H_2O} = P_{sat, H_2O} / (R_{H_2O} * T). Participants emphasize the importance of unit consistency in calculations and point out the physical inaccuracies in the problem's phrasing regarding saturation conditions.

PREREQUISITES
  • Understanding of the ideal gas law
  • Knowledge of saturation pressure for water vapor
  • Familiarity with specific gas constants, particularly R_{H_2O}
  • Basic thermodynamic principles related to air and humidity
NEXT STEPS
  • Research the calculation of saturation pressure for water vapor at various temperatures
  • Learn about the implications of unit conversions in thermodynamic equations
  • Explore the concept of relative humidity and its relationship with saturation vapor pressure
  • Study the physical properties of gases under varying temperature and pressure conditions
USEFUL FOR

Students in thermodynamics, meteorologists, and anyone involved in HVAC system design or atmospheric science will benefit from this discussion.

Orbital
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Homework Statement


Estimate the mass of water vapor that is contained in 1 m^3 of saturated air at a temperature of plus 20 degrees Celsius

2. The attempt at a solution
I looked up the saturation pressure for water vapor at the given temperature. Can I just use the ideal gas-law for the mass? i.e. is the solution as simple as
m_{H_2O} = \frac{P_{sat, H_2O}}{R_{H_2O}T}
or do I have to make another approach?
 
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yes this looks right, but -as usual- be careful with the units
 
Last edited:
Can you tell me why the phrasing of the problem is physically incorrect?
 

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