Ideal vs. Real Gases No gas is ideal. As the temperature of a gas increases and the pressure on the...
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Transcript of Ideal vs. Real Gases No gas is ideal. As the temperature of a gas increases and the pressure on the...
Real Gases Do Not Behave Ideally
CH4
H2
N2
CO2
Idealgas
2.0
1.0
00 200 400 600 800 1000
P (atm)
PVnRT
Equation of State of an Ideal Gas
• Robert Boyle (1662) found that at fixed temperature– Pressure and volume of a gas is inversely proportional
PV = constant Boyle’s Law
• J. Charles and Gay-Lussac (circa 1800) found that
at fixed pressure– Volume of gas is proportional to change in temperature
Volume
Temp-273.15 oC
All gases extrapolate to zero volume at a temperature corresponding to –273.15 oC (absolute zero).
He CH4
H2O
H2
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
T1 T2
V1 V2=
(Pressure is held constant)
T1 T2
P1 P2=
(Volume is held constant)
CharlesCharles Gay-LussacGay-Lussac
Kelvin Temperature Scale
• Kelvin temperature (K) is given by
K = oC + 273.15 where K is the temperature in Kelvin, oC is temperature in Celcius
• Using the ABSOLUTE scale, it is now possible to write Charles’ Law as
V / T = constant Charles’ Law• Gay-Lussac also showed that at fixed volume
P / T = constant • Combining Boyle’s law, Charles’ law, and Gay-Lussac’s law,
we have
P V / T = constant
Gay-Lussac
Charles