Difference between revisions of "Ideal Gas Law"

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The ideal gas law, or universal gas equation, is an equation of state of an ideal gas. It combines several gas laws (i.e., [[Dalton’s Law]], [[Boyle’s Law]], [[Charles Laws]]):  
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The '''ideal gas law''', is an [[equation of state]] for an ideal gas. It combines three [[gas]] laws ([[Dalton’s Law]], [[Boyle’s Law]] and [[Charles' Law]]) into one equation:  
  
PV = nRT
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:PV = nRT
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where
 
   
 
   
P is the pressure of gas in pascals;   
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*P is the [[pressure]] of gas;   
V the volume it occupies in cubic meters;  
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*V the [[volume]] the gas occupies;  
T the temperature of the gas in degrees Kelvin;  
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*T the absolute [[temperature]] (meaning it must be in [[Kelvin]] or [[Rankine]];  
n is the molar mass of the gas occupying the volume V;  
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*n is the number of moles of the gas occupying the volume V;  
R is the gas constant  
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*R is the [[gas constant]].
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The gas constant can be expressed in any number of units, but the most common representations are 0.0821 <math>\frac{L \cdot atm}{mole \cdot K}</math> or 8.314 <math>\frac{J}{mole \cdot K}</math>
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==Ideal Gas==
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The equation is valid only for an ideal gas, the hypothetically perfect embodiment of a gas in which the particles ([[atom]]s or [[molecule]]s) in the gas are spherical, identical, have no [[volume]], and experience no intermolecular forces between them. All collisions between the particles or the particles and the container are perfectly [[elastic collision|elastic]]. 
  
R = 0.0821 <math>\frac{L \cdot atm}{mole \cdot K}</math> or 8.314 <math>\frac{J}{mole \cdot K}</math>
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Since this is just a model, real gases only obey the ideal gas law approxamately, not perfectly. Generally, the ideal gas assumption is accurate for unreactive gases at high temperature and/or low pressure. A good rule of thumb is that the assumption can be used above room temperature and below 1 [[atmosphere]] of pressure.
  
The equation is valid only for an ideal gas. Real gases obey this equation only approximately, but its validity increases as the density of the gas tends to zero.
 
 
[[category:physics]]
 
[[category:physics]]
 
[[category:chemistry]]
 
[[category:chemistry]]

Revision as of 16:55, 20 September 2007

The ideal gas law, is an equation of state for an ideal gas. It combines three gas laws (Dalton’s Law, Boyle’s Law and Charles' Law) into one equation:

PV = nRT

where

The gas constant can be expressed in any number of units, but the most common representations are 0.0821 or 8.314

Ideal Gas

The equation is valid only for an ideal gas, the hypothetically perfect embodiment of a gas in which the particles (atoms or molecules) in the gas are spherical, identical, have no volume, and experience no intermolecular forces between them. All collisions between the particles or the particles and the container are perfectly elastic.

Since this is just a model, real gases only obey the ideal gas law approxamately, not perfectly. Generally, the ideal gas assumption is accurate for unreactive gases at high temperature and/or low pressure. A good rule of thumb is that the assumption can be used above room temperature and below 1 atmosphere of pressure.