Combined and Ideal Gas Laws
The combined gas law or general gas equation is formed by the combination of the three laws, and shows the relationship between the pressure, volume, and temperature for a fixed mass of gas:
With the addition of Avogadro's law, the combined gas law develops into the ideal gas law:
where
- P is pressure
- V is volume
- n is the number of moles
- R is the universal gas constant
- T is temperature (K)
where the constant, now named R, is the gas constant with a value of .08206 (atm∙L)/(mol∙K). An equivalent formulation of this law is:
where
- P is the absolute pressure
- V is the volume
- N is the number of gas molecules
- k is the Boltzmann constant (1.381×10−23 J·K−1 in SI units)
- T is the temperature (K)
These equations are exact only for an ideal gas, which neglects various intermolecular effects (see real gas). However, the ideal gas law is a good approximation for most gases under moderate pressure and temperature.
This law has the following important consequences:
- If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas.
- If the temperature and volume remain constant, then the pressure of the gas changes is directly proportional to the number of molecules of gas present.
- If the number of gas molecules and the temperature remain constant, then the pressure is inversely proportional to the volume.
- If the temperature changes and the number of gas molecules are kept constant, then either pressure or volume (or both) will change in direct proportion to the temperature.
Read more about this topic: Gas Laws
Famous quotes containing the words combined, ideal, gas and/or laws:
“The real accomplishment of modern science and technology consists in taking ordinary men, informing them narrowly and deeply and then, through appropriate organization, arranging to have their knowledge combined with that of other specialized but equally ordinary men. This dispenses with the need for genius. The resulting performance, though less inspiring, is far more predictable.”
—John Kenneth Galbraith (b. 1908)
“There is no dream of love, however ideal it may be, which does not end up with a fat, greedy baby hanging from the breast.”
—Charles Baudelaire (1821–1867)
“one pale woman all alone,
The daylight kissing her wan hair,
Loitered beneath the gas lamps’ flare,
With lips of flame and heart of stone.”
—Oscar Wilde (1854–1900)
“If woman alone had suffered under these mistaken traditions [of women’s subordination], if she could have borne the evil by herself, it would have been less pitiful, but her brother man, in the laws he created and ignorantly worshipped, has suffered with her. He has lost her highest help; he has crippled the intelligence he needed; he has belittled the very source of his own being and dwarfed the image of his Maker.”
—Clara Barton (1821–1912)