Which unit of pressure is used in the ideal gas law?

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SUMMARY

The ideal gas law, expressed as P = N x R x T, defines pressure (P) in relation to density (N), the ideal gas constant (R), and temperature (T). In this discussion, the values used are N = 1.204 kg/m³, R = 8.314472 J/(mol·K), and temperatures of 293.15 K and 12000 K, resulting in pressures of 2934.61 Pa and 120127.49 Pa, respectively. The pressure unit is confirmed to be in Pascals (Pa), as absolute values are required for both pressure and temperature in the equation.

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  • Understanding of the ideal gas law and its components
  • Familiarity with units of pressure, specifically Pascals (Pa)
  • Knowledge of the ideal gas constant (R) and its units
  • Basic principles of thermodynamics and gas behavior
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escapistgoat
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The ideal gas law states that pressure (P) is equal to the product of density (N), the ideal gas constant (R) and temperature (T):

P = N x R x T

I can't figure out which unit the pressure is actually in, although it does seems to work out as the figure I'm supposed to get with a 11706.85° increase in temperature is around 40x the pressure at 293.15° Kelvin:

N = 1.204 kg/cubic metre
R = 8.314472
T = 293.15
P = 2934.61

N = 1.204 kg/cubic metre
R = 8.314472
T = 12000
P = 120127.49

Thank you for considering this!

- Gordon
 
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escapistgoat said:
The ideal gas law states that pressure (P) is equal to the product of density (N), the ideal gas constant (R) and temperature (T):

P = N x R x T

I can't figure out which unit the pressure is actually in, although it does seems to work out as the figure I'm supposed to get with a 11706.85° increase in temperature is around 40x the pressure at 293.15° Kelvin:

N = 1.204 kg/cubic metre
R = 8.314472
T = 293.15
P = 2934.61

N = 1.204 kg/cubic metre
R = 8.314472
T = 12000
P = 120127.49

Thank you for considering this!

- Gordon

The units must only be dimensionally correct. Absolute values are used for pressure and temperature.

CS
 
You need to start by writing the ideal gas law as P =RT/V, and substituting in the units for

R (joules/mol °K), T (°K), and V (m3).

[added] In this situation, V is actually in units of m3/mol

Bob S
 
Last edited:

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