the equation of state ideal or perfect gas ideal gas law , reads
p
v
=
n
r
t
,
{\displaystyle pv=nrt,}
where p pressure, v volume, n amount of gas (in mol units), r universal gas constant, 8.314 j/(mol k), , t temperature. written way, called chemist s version , since emphasizes number of molecules n. can written as
p
=
ρ
r
s
t
,
{\displaystyle p=\rho r_{s}t,}
where
r
s
{\displaystyle r_{s}}
specific gas constant particular gas, in units j/(kg k), , ρ = m/v density. notation gas dynamicist s version, more practical in modeling of gas flows involving acceleration without chemical reactions.
the ideal gas law not make assumption specific heat of gas. in general case, specific heat function of both temperature , pressure. if pressure-dependence neglected (and possibly temperature-dependence well) in particular application, gas said perfect gas, although exact assumptions may vary depending on author and/or field of science.
for ideal gas, ideal gas law applies without restrictions on specific heat. ideal gas simplified real gas assumption compressibility factor z set 1 meaning pneumatic ratio remains constant. compressibility factor of 1 requires 4 state variables follow ideal gas law.
this approximation more suitable applications in engineering although simpler models can used produce ball-park range real solution should lie. example ideal gas approximation suitable inside combustion chamber of jet engine. may useful keep elementary reactions , chemical dissociations calculating emissions.
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