Solving a Problem with Air Mass: Calculating Pressure & Volume

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SUMMARY

The discussion focuses on calculating the new volume of an air mass using the combined gas law, given initial conditions of pressure, volume, and temperature. The original parameters are a volume of 1200 m³, pressure of 101 kPa, and temperature of 288 K, which change to a pressure of 80 kPa and temperature of 270 K. The correct formula to use is the combined gas law, expressed as (P1*V1)/T1 = (P2*V2)/T2, allowing for the calculation of the new volume (V2) as V2 = (P1*V1*T2)/(T1*P2). This method ensures accurate results by maintaining consistent units throughout the calculations.

PREREQUISITES
  • Understanding of the Ideal Gas Law (PV = nRT)
  • Familiarity with the Combined Gas Law
  • Basic knowledge of pressure, volume, and temperature relationships
  • Ability to perform unit conversions in scientific calculations
NEXT STEPS
  • Study the Combined Gas Law in detail, including derivations and applications
  • Learn about unit conversions for pressure, volume, and temperature
  • Explore real-world applications of the Ideal Gas Law in meteorology
  • Practice solving problems involving changes in state for gases
USEFUL FOR

Students in physics or engineering, meteorologists, and anyone interested in thermodynamics and gas behavior will benefit from this discussion.

Izekid
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Hi!
I have problem with this ...

A airmass with the volume 1200m^3 the presswure 101kPa and the temperature 288K moves vertical upwards. The pressure sinks to 80kPa and the temperature sinks to 270K.

Calculate the new pressure and I know how to use it

I take 101*1200/288 = 420 Is this right?

because v1*p1 /t1 = v2*p2/t2
And how do i make an equation of this?

and the second question is... how big volume would the airmass had in the normal conditions? Use that to calculate the airs mass...

And PLEASE no answer like this ... Use the Ideal Gas law... NO **** I had already found out that ...
 
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For the first half.. originally, you are given pressure, volume, and temp.
Pressure and temperature changes, so you should solve for volume, not pressure.

P*V = n*R*T

What you DON'T know, and have to calculate with the original three conditions is n*R.

Same gas, or mixture, n*R will be the same for the new pressure, temp and volume.
 
Last edited:
use the combined gas law

you have everything but v2
v2 = x (unkown volume)

(p1*v1)/t1 = (p2*X)/t2 solve for x (rearrange)

x= (p1*v1*t2)/ (t1*p2)

make sure your units are right
 

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