The Properties of Gases. 박영동 교수 자연과학대학 화학과. 기체는 왜 다루는가 ?. 역사적인 배경과 의미 Boyle’s Law – First Scientific Experiment, 1661 Charles’s Law – Definition of Temperature, 1780s Avogadro’s Hypothesis –
역사적인 배경과 의미
Boyle’s Law – First Scientific Experiment, 1661
Charles’s Law – Definition of Temperature, 1780s
Avogadro’s Hypothesis –
Combined Ideal Gas Law and Kinetic Theories– First Successful Scientific Law derived from purely mathematical approach.
실용적인 배경과 의미
기체는 열역학의 기초, 열역학 제1, 2 법칙을 설명
화학 평형, 화학적 퍼텐셜의 기초
화학반응의 근본적 이해를 도움- 반응동력학
기체를 다루는 공정 이해에 중요한 기초를 줌
pressure is the force F acting on an area A
N/m2 = Pa(pascal)
1 atm = 1.013×105 Pa = 760 torr
1 bar = 1×105 Pa
Boyle’s law in 1660.
Isotherms of an ideal gas and a real gas.
an ideal gas and a real gas
Charles’s law in 1780s.
Avogadro’s principle in 1811.
Charles’s law and a perfect gas
Dalton’s concept of partial pressure in 1801.
Partial pressure of idea gases
very small particles, all with non-zero mass.
in constant, random motion.
perfectly elastic collisions with the walls.
negligible interactions among molecules except collisions.
The total volume of the gas molecules is negligible.
The molecules are perfectly spherical in shape, and elastic.
no relativistic effects.
no quantum-mechanical effects.
instant collision with the wall.
The equations of motion of the molecules are time-reversible.
an ideal gas in a container of side l
Kinetic model of an ideal gas for basics
Click here to see KineticTheory_of_Gas.pdf
Effusion rate ∝c∝(T/M)1/2
(a) Diffusion, (b) Effusion
number density of molecules = N/V = nNA/V = pNA/RT
sweep volume= ‘c’ σ
collision rate z =‘c’ σ × number density of molecule
mean free path λ= RT/(21/2NAσp)
cross sectional area σ= πd2
finite sizes of molecules
Phase transition and the critical temperature
Interaction between molecules
potential energy variation
Isotherms of CO2
CO2 at the pressure of 75 atm
Compression factor at 0 ℃
accessible volume is smaller than the physical volume due to the molecular volume.
pressure measured is smaller than the ‘ideal’ pressure due to the attractions between molecules.
van der Waals isotherms
interpretation of the van der Waals equation
The principle of the Linde refrigerator.