Chemistry 8 - Gas Properties, Laws, and Pressure

What is the Kinetic Molecular Theory?

A molecular explanation of gases determined by 5 postulates and developed gas laws

What are the 5 postulates of the KMT?

1. Gases consist of tiny particeles which are so small, when compared, the volume of the gap between particles is negligble/zero.
2. There are no attractive (IMF) or repulsive froces between gas molecules.
3. Particles move in a constant random straight line motion unless they collide w molecules or the walls of a cointainer - these collisions cause pressure exerted by gas.
4. Molecules collide elastically or have no loss of KE.
5. KE is directly proportional to Kelvin Temperature of gas.

What are the characteristics of gases?

- Expand to fill any container
> random motion; no attractive forces
- Gases are fluid
> no attraction/replusion
- Gases have very low densities
> No vol = Lots of empty space
- Gases are compressible
> No vol = lots of empty space
- Gases undergo diffusion and effusion
> Random Motion

What are the properties of gases? Units?

Volume (V)
- Liters (L)
Pressure (P)
- Atmosphere (atm), kilopascal (kPa, mmHg, torr),
Temperature (T),
- Kelvin (K)
Number of molecules (n)
- Mole (n)

How do gases exert pressure?

By colliding with other particles or the wall - more collisions = more pressure

What are factors that affect gas pressure?

Amount of gas, volume, and temperature

How does the amount of gas affect gas pressure?

More Particles = More Pressure because more collisions

How does the volume of gas affect the pressure?

Less Volume = More pressure bc less volume means less space therefore more collisions

How does the temperature of the gas affect pressure?

Higher pressure = Higher KE = more collisions = higher pressure

What is the pressure conversion?

1atm=760 mmHg=760torr=101.3kPa

What is boyle's law?

P1V1 = P2V2 where temp is held constant - pressure and volume are inversely proportional

What is charles' law?

V1/T1 = V2/T2 where pressure is held constant -volume and temperature are directly proportional

What is Gay-Lussac's Law?

P1/T1 = P2/T2 where volume is held constant - pressure and temperature are directly proportional