Gas Density vs. Temperature
The relationship between the mass and volume of a substance is referred to as density and defined by the formula of density equals mass divided by volume (density equals mass/volume). Put another way, density tells how much space is occupied by a given amount of matter. Both temperature and pressure affect the volume of a substance and consequently the density. Thus, the density of a substance is often given in relation to a specific temperature and pressure.
Other People Are Reading
-
Kinetic Theory
-
All matter is made of tiny particles. The amount of energy in each particle translates into the temperature of the particle. The more energy the particle has, the higher the temperature. The state of matter (solid, liquid, or gas) depends on the amount of energy in each particle and the attraction between the individual particles.
Gases
-
Gases are easily distinguished from liquids and solids by their shape and volume. While solids have a rigid shape and volume and liquids have a fluid shape but a relatively rigid volume, gases exhibit an elastic shape and volume. This fluidity in shape and volume results from the high energy of the particles overcoming attractions between the particles. This high energy allows gases to expand or compress in volume and flow to fit any shape.
-
Charles' Law
-
While the temperature of a substance fundamentally determines whether a substance is a solid, liquid, or gas, the temperature also determines the volume of gases. Assuming the pressure and amount of gas are constant, increasing the temperature of a gas will result in a corresponding increase in the volume. This relationship between temperature and volume is known as Charles' Law.
Ideal Gas Law
-
Charles' Law and other observations of gases are incorporated into the Ideal Gas Law. The Ideal Gas Law states that in an ideal gas the relationship between pressure, volume, temperature, and mass as PV = nRT, where P is pressure, V is volume, n is the number of moles (a measure of mass), R is the gas constant, and T is temperature. While this law specifically applies to ideal gases, most gases approximate the Ideal Gas Law under most conditions. Of particular note is the inclusion of density (mass and volume) and temperature, indicating a relationship between these three properties.
Temperature and Gas Density
-
Observing a relationship between the volume and temperature if a gas, it should be expected that there is also a relationship between the temperature and density of a gas since density is derived in part from the volume. This indeed is the case as gases decrease in density (assuming a constant pressure) as the temperature increases. In terms of the kinetic theory, as the energy of the particles increase (temperature rises) they disperse farther apart (increase volume). Conversely, as the temperature of a gas drops, the density of the gas decreases.
-
References
Resources
- Photo Credit Hot air balloon image by MAXFX from Fotolia.com
