Chemistry 10: The Properties of Gases

Kinetic Molecular Theory (KM)

1. gas molecules move in random straight-line motion

2. gas molecules undergo elastic collisions with their container walls and other particles

Differentiate between diffusion

flow of a gas through a small orifice and effusion - mixing of gases in a system of gases

Four characteristic that are needed to completely define a gas

pressure, number of moles, volume, temperature

pressure

force per unit area, # of collisions per defined area

volume

usually defined as the volume of its containerte

temperature

always use kelvin

torrs

mmHg

STP Standard Temperature and Pressure conditions

0 degrees celcius, 273.15K, 1 ATM

standard molar volume

1 mole of any gas at STP occupies 22.4L

Boyle’s Law

when the temperature and number of moles of a gas are held constant, the pressure of the gas varies indirectly with its volume

Charle’s Law

when the pressure and number of moles of a gas are held constant, the volume of the gas vaires directly with its temperature

Gay-Lussac’s Law

when the volume and number of moles of a gas are held constant, the pressure vaires directly with its temperature

Avagardro’s Law

when pressure and temperature of a gas are held constant the volume of a gas varies directly with the number of moels of the gas (opposite of Gay- Lussac’s Law)

In each of the four laws, there are always

two variable which change and two which remain constant

Combined Gas Law

Use this formula when you have one of the four characterisitcs changing. If one of the four is not mentioned, assume STP and ignore the variable.

Dalton’s Law

the sum of the partial pressures of the gases in a system equals the total presure to solve partial pruesure gas law problems. the total pressure is usually read directly from the barometer