1. Kinetic molecular theory explains gas behavior, introduced by Daniel Bernoulli, expanded by Maxwell & Boltzmann
2. Gases consist of molecules (mono‑atomic, diatomic, poly‑atomic).
3. Molecules occupy negligible volume compared to container volume.
4. Molecules move in random, straight‑line motion; distance between collisions = mean free path.
5. Collisions are elastic (no energy loss).
6. Gas pressure results from molecules hitting container walls.
7. No attraction or repulsion between molecules (ideal assumption).
8. Kinetic energy of molecules ∝ absolute temperature.
9. Kinetic equation:
10. Mean square velocity averages the squares of molecular velocities:
11. Atmospheric pressure = 760 torr at sea level (0 °C).
12. Barometer measures air pressure with mercury.
13. Manometer measures gas pressure in a container.
14. Pressure = Force ÷ Area; SI unit = pascal (Pa) = N/m².
15. Conversions: 101325 Pa = 1 atm = 760 mm Hg = 14.7 psi.
16. Absolute zero = –273.15 °C = 0 K; theoretical temperature where ideal gas volume → 0.
17. Charles’s Law: volume ∝ absolute temperature (constant pressure).
18. Boyle’s Law: volume ∝ 1/pressure (constant temperature).
19. Avogadro’s Law: equal volumes of gases at same T & P contain equal moles; \(V \propto n\).
20. Ideal gas equation merges Boyle’s, Charles’s & Avogadro’s laws:(PV = nRT).
21. Gas constant (R) = 0.0821 atm dm³ mol⁻¹ K⁻¹ or 8.31 J mol⁻¹ K⁻¹.
22. Van der Waals equation corrects for molecular volume and intermolecular forces.
23. Volume correction: real volume = ideal volume − nb; b depends on molecular size.
24. Pressure correction: real pressure < ideal pressure due to intermolecular attractions.
.25. Dalton’s Law: total pressure = sum of partial pressures; Ptotal = …
26. Graham’s Law: rate of effusion/diffusion of a gas is inversely proportional to the square root of its molar mass (or density) at constant T & P.
27. Liquefaction of gases: achieved by high pressure + low temperature; each gas has a critical temperature & critical pressure.
28. Joule‑Thomson effect: gas expands from high to low pressure → cooling, used for liquefaction.
29. Liquid air uses: LNG (liquefied natural gas), LPG (liquefied petroleum gas), liquid ammonia (refrigerant), liquid oxygen (welding), liquid nitrogen (medical).
30. Plasma: fourth state of matter; ionized gas with equal electrons & ions, affected by electric/magnetic fields, used in lamps, TVs, cutting torches & semiconductor processing.