Chemistry - Gas Properties and Laws

lesson 1

A gas is a state of matter that has no definite shape and no definite volume.

Air inside a balloon: takes the shape of the balloon.

gases can be compressed readily

Gases are easy to squeeze because their particles are spread out with lots of space between them.

KMT - Kinetic Molecular Theory

It is a theory that explains how particles (atoms or molecules) in matter move.

Principal assumptions of KMT

1. Gases are made up of tiny particles

2. There is no force of attraction between and among molecules

3. gas molecules are in a constant random and linear motion

4. collisions are perfectly elastic

5. the average kinetic energy depends on the temperature

Pressure

force per unit of a gas particle when they exert and collide with the wall of the container

Temperature

measure of the average kinetic energy of the particles

Volume

amount of space that a substance occupies

Boyle’s Law

Gas Law - relationship of pressure and volume

P₁V₁ = P₂V₂

V₁ = initial volume

V₂ = final volume

P₁ = initial pressure

P₂ = final pressure

General formula of boyle’s law

At constant temperature, pressure and Volume have an inverse relationship.

The smaller the space = increase of pressure (because of frequent collisions)

Define the relationship of Pressure and volume according to Boyle’s law

Charles’s Law

Gas Law - relationship of volume and temperature

V₁/T₁ = V₂/T₂

V₁ = initial volume

V₂ = final volume

T₁ = initial temperature

T₂ = final temperature

General formula of charles’s law

at constant pressure, volume and temperate have a direct relationship

hotter particles (faster and spread out) = need more space

Define the relationship of volume and temperature according to charles’s law

Avogrado’s Law

Gas law - relationship of volume and number of moles

V₁/n₁ = V₂/n₂

V₁ = initial volume

V₂ = final volume

n₁ = initial number of molecules

n₂ = final number of molecules

General formula of Avogrado’s Law

At the same temperature and pressure, equal volumes of gases contain the same number of particles (molecules). - direct relationship

If you add more gas particles (moles), the volume increases—provided temperature and pressure don’t change.

define the relationship of volume and number of molecules according to avogrado’s law

Gay-Lussac’s Law

Gas Law - relationship of pressure and temperature

P₁/T₁ = P₂/T₂

P₁ = initial pressure

T₁ = initial temperature

P₂ = final pressure

T₂ = final temperature

general formula for gay-lussac’s law

The pressure of a gas is directly proportional to its temperature, if volume and number of moles are constant.

Heat makes particles move faster, hitting the container walls harder, so pressure increases.

Define the relationship of temperature and pressure according to gay-lussac’s law

Ideal Gas law

Gas Law - relationship of all four variables combined into a single expression

PV = nRT

P: pressure

V: volume

n: number of molecules

R: ideal gas constant

T: temperature

general formula for ideal gas law

Combines all the gas laws into one equation relating pressure, volume, temperature, and moles.

define the relationship of all variables in ideal gas law