ideal gas sys eqns

  • equation of state
  • isobaric process
  • isochoric process
  • isothermal process
  • adiabatic process
  • work
  • heat
  • internal energi change
  • heat capacity ratio
  • cycle
  • entropy
  • the 1st law of thermodynamics
  • the 2nd law of thermodynamics

ideal gas sys eqns

· 2 mins read

Equations used in an ideal gas system are listed here, but they might be not complete.

equation of state

Ideal gas obeys equation of state

$$\tag{1} PV = nRT, $$

known as the ideal gas law 1, with $P$ is pressure, $V$ is volume, $n$ is number of moles of gas, $R$ is universal gas constant, and $T$ is temperature.

isobaric process

An isobaric process is a thermodynamic process in which the pressure remains constant 2, where the state variables are

$$\tag{2a} P_j = P_i, $$

$$\tag{2b} V_j \ne V_i, $$

$$\tag{2c} T_j \ne T_i, $$

in this process from state $i$ to state $j$.

specific heat ratio

It is an additional variable in ideal gas system 3

$$\tag{9} \gamma = \frac{c_p}{c_v}, $$

where at different temperature different gas has different value4.

refs

  1. The Editors of Encyclopaedia Britannica “ideal gas law”, Encyclopedia Britannica, 12 Feb 2025, url https://www.britannica.com/science/ideal-gas-law [20250312]. ↩︎

  2. Andrew Zimmerman Jones, “What Is Isobaric Process?”, ThoughtCo, 30 Jun 2019, url https://www.thoughtco.com/p-2698984 [20250313]. ↩︎

  3. Nancy Hall (ed), “Specific Heats”, National Aeronautics and Space Administration, 13 May 2021, url https://www.grc.nasa.gov/www/k-12/airplane/specheat.html [20250313]. ↩︎

  4. Knowino contributors, “Specific heat ratio”, Knowino, an encyclopedia, 19 Dec 2010, url https://www.theochem.ru.nl/~pwormer/Knowino/knowino.org/w/index306d.html?oldid=4599 [20250313]. ↩︎