Gases

Characteristics of Gases


Although different gasses may differ widely in their chemical properties, they share many physical properties

Characteristics of Gases

The air we breathe:

Some common gases:

Formula

Name

Characteristics

H2

Hydrogen

Flammable, lighter than air

He

Helium

Colorless, nonflammable, lighter than air

HCN

Hydrogen cyanide

Toxic, has been used historically to shorten people's lives

HCl

Hydrogen chloride

Toxic, corrosive

H2S

Hydrogen sulfide

Toxic, smells like rotten eggs

CO

Carbon monoxide

Toxic, Jack Kervorkian's favorite gas

CO2

Carbon dioxide

Colorless, odorless, not toxic, but unsupportive of respiration

CH4

Methane

Colorless, odorless, flammable, occasional byproduct of the digestive system

N2O

Nitrous oxide

Colorless, sweet odor, makes you feel "funny"

NO2

Nitrogen dioxide

Toxic, red-brown, irritating odor

NH3

Ammonia

Colorless, pungent odor

SO2

Sulfur dioxide

Colorless, irritating odor

All of the above gasses

Substances that are liquids or solids under standard conditions can usually also exist in the gaseous state, where they are commonly referred to as vapors

Some general characteristics of gasses which distinguish them from liquids or solids:

    1. In air, the molecules take up about 0.1% of the total volume (the rest is empty space)
    2. Each molecule, therefore, behaves as though it were isolated (as a result, each gas has similar characteristics)