Chemistry chapter 13 : Gases

Introduction to Chemistry a Foundation

Pressure

The force per unit area exerted on a surface; measured in units such as atm, kPa, or mmHg.

Barometer

An instrument used to measure atmospheric pressure.

Atmosphere (atm)

A unit of pressure defined as being exactly equivalent to 760 mm Hg.

Pascal (Pa)

The SI unit of pressure, equal to a force of one newton per square meter.

Partial Pressure

The pressure exerted by each gas in a mixture.

Dalton’s Law of Partial Pressures

States that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases.

Kinetic-Molecular Theory

Describes the behavior of matter in terms of particles in motion. Collisions between particles are perfectly elastic, meaning that there is no net loss of total kinetic energy.

Elastic Collision

A collision between gas particles or between particles and container walls in which no kinetic energy is lost.

Temperature

A measure of the average kinetic energy of the particles in a sample of matter.

Diffusion

The movement of one material through another from an area of higher concentration to an area of lower concentration.

Effusion

The process by which gas particles pass through a tiny opening.

Graham’s Law of Effusion

States that the rate of effusion for a gas is inversely proportional to the square root of its molar mass.

Boyle’s Law

States that the volume of a given amount of gas held at constant temperature varies inversely with the pressure.

Charles’s Law

States that the volume of a given mass of gas is directly proportional to its temperature in kelvins at constant pressure.

Gay-Lussac’s Law

States that the pressure of a given mass of gas varies directly with the kelvin temperature when the volume remains constant.

Combined Gas Law

Combines Boyle’s, Charles’s, and Gay-Lussac’s laws into one relationship: \frac{P1V1}{T1} = \frac{P2V2}{T2} .

Avogadro’s Principle

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

Molar Volume

The volume that one mole of a gas occupies at 0°C and 1 atm pressure; equal to 22.4 L.

Ideal Gas Law

Describes the physical behavior of an ideal gas in terms of pressure, volume, temperature, and number of moles: PV=nRT

Ideal Gas Constant (R)

The constant in the ideal gas law with the value 0.0821 L·atm/mol·K.

Ideal Gas

A hypothetical gas whose particles take up no space and have no intermolecular attractive forces.

Real Gas

A gas that does not behave completely according to the assumptions of the kinetic-molecular theory.

Absolute zero

Coldest possible tempeture