Atmospheric Pressure & Boiling Point of Water: 20 C

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SUMMARY

The boiling point of water at 20°C requires an atmospheric pressure of approximately 25 mbar, as derived from the Clausius-Clapeyron equation. This equation relates the change in vapor pressure with temperature and is essential for understanding phase changes in pure substances. Impurities, such as salt, alter the boiling point by affecting hydrogen bonding, necessitating a different calculation. Accurate arithmetic is crucial, as initial calculations may lead to incorrect conclusions.

PREREQUISITES
  • Understanding of the Clausius-Clapeyron equation
  • Basic algebra skills for calculations
  • Knowledge of phase changes in pure substances
  • Familiarity with steam tables and their application
NEXT STEPS
  • Study the Clausius-Clapeyron equation in detail
  • Learn how to interpret steam tables for various substances
  • Explore the effects of impurities on boiling points
  • Practice calculations involving vapor pressure and temperature relationships
USEFUL FOR

Students in chemistry, physicists, and anyone interested in thermodynamics and the properties of water under varying atmospheric conditions.

ybhathena
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What does the atmospheric pressure have to be to make the boiling point of water 20 C?
 
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Google "Clausius-Clapeyron equation" and apply it...
 


Oh ok that seems to be what I need. Its a little bit advanced, could you explain the general idea of how to use this formula? I am a bit new
 


Hmm... Well that would be a very involved answer. You should be able to handle it if you know basic algebra. I'm assuming you were given the values to plug in. Also it assumes that it's pure water. Impurities such as salt require the chemical process to first break the hydrogen bonds making water boil at a higher temperature.

I did it for you quickly and got an an answer of 18,900m rounded.

Edit: Actually that can't be correct. That's the limit where water boils at the internal temperature of a human, 37 C. I must have messed up my arithmetic.
 
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