Unit 7: Gases

properties of gases

expansion, fluidity, low density, compressibility, diffusion and effusion

kinetic molecular theory

the theory that all matter is composed of particles (atoms and molecules) moving constantly in random directions

pressure

the amount of force exerted per unit area of a surface

temperature

A measure of the average energy of motion of the particles of a substance.

kinetic energy

the energy an object has due to its motion

how to convert between kPa, mmHg, Torr atm

101.3 kPa = 1 atm = 760 torr = 760 mmHg

STP and SATP

STP is 0 degrees celsius

Standard temperature and pressure

SATP is 25 degrees celsius

standard ambient temperature and pressure

Kelvin Temperature

C + 273 = K

0 kelvin is absolute 0

Boyle's Law

if the temperature and the mass of a gas are kept constant, then the volume of the gas is inversely proportional to the applied pressure.

P1V1 = P2V2

Gay-Lussac's Law

the pressure of a gas is directly proportional to the Kelvin temperature if the volume is constant

P1/T1 = P2/T2

Dalton's law or partial pressures

the total pressure of a gas mixture is the sum of the partial pressures of the individual gases

Pt = P1 + P2 + P3. + ..........

molar volume of a gas

the space occupied by 1 mol of gas

at SATP molar volume is 24.8L/mol

at STP molar volume is 22.4L/mol

n = V/Vm

Charles Law

The volume of a fixed mass of gas is proportional to its temperature in kelvins when the pressure remains constant

V1/T1 = V2/T2

Combined Gas Law

the relationship between the pressure, volume, and temperature of a fixed amount of gas

P1V1/T1 = P2V2/T2

Avogadro's Law

equal volumes of gases at the same temperature and pressure contain equal numbers of particles

n1/V1 = n2/V2

Ideal Gas Law

PV = nRT; relates pressure, volume, temperature, and moles. R in this case is the universal gas constant = 8.314

Temperature must be in kelvins(K)

volume must be in litres(L)

pressure must be in kilopascals(kPa)