Gases

Gases are

easily compressed and expand to completely fill a container (they are mostly empty space).

Temperature, Speed and Kinetic Energy are

proportional. Higher temp —> higher speeds —> higher KE

The attractive forces between gas molecules are

weak

Gas Pressure

The force (pressure) exerted by gas colliding with the walls of a container

Pressure

Force area per unit area (F/A)

Pascal (Pa)

the SI unit of pressure. (Also) atm, torr, mmHg and psi. ( 1 atm = 760 torr = 760 mmHg).

Barometric Pressure

The pressure exerted by the atmosphere. It is measured by a barometer. Standard pressure is 1 atm or 760 torr.

Manometer

A device which measures the pressure of a gas

Boyle’s Law

At a constant TEMPERATURE, pressure of a gas is inversely proportional to its volume. Formula = P1 x P2 = P2 x V2

Charles’s Law

At a constant PRESSURE, the volume of a gas is directly proportional to its temperature. Formula: V1/T1 = V2/T2

Avogadro’s Law

At constant TEMPERATURE & PRESSURE, the volume of a gas is directly proportional to the number of moles of gas. Formula: V1/n1 = V2/n2

Boyles', Charles’s & Avogadro’s Law can be combined

Ideal Gas Law

Ideal Gas Law

FORMULA: PV = nRT

Assumes: There is no interaction between gas molecules and that gas molecules do not occupy any space.

P =

Pressure in atm

V =

Volume in Liters

n =

moles

R =

(0.08206 Lxatm/ molxK). R is our constant.

T =

Temperature in Kelvin. Celsius to K conversion = (C + 273)

Dalton’s Law of Partial Pressures

For a mixture of 2 ideal gases: Ptotal = P_A + P_B. P_A is the partial pressure of A. The pressure caused by wall collisions of gas A. P_B is the partial pressure of A. The pressure caused by wall collisions of gas B.

Mol fraction =

X_A. Can be found by P_A/P_total = n_A/n_total

An ideal gas

An ideal gas has a high temp and low mass. (KE is proportional to TEMP) Ideal gasses don’t really exist. But when comparing 2 gases you can see which acts more ideal.