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# What is the relationship between the pressure and volume of a gas?

Describe the relationship between the pressure and volume of a gas.
by RGP
Member since:
September 05, 2006
Total points:
831 (Level 2)

## Best Answer - Chosen by Voters

In general, the relationship between pressure and volume of a gas is unknown and must be determined experimentally. However, a large number of real gases can be modeled as ideal gases. The basic assumption behind the ideal gas model is that individual molecules of the gas do not interact. The ideal gas equation of state is given as

PV=nRT

where P is pressure, V is volume, n is number of particles, R is the ideal gas constant, and T is temperature. Knowing something about the number of particles and the temperature can yield an expression relating P and V. For example, for a closed system (n is constant) at constant temperature (T is constant), we have

PV=constant

which is commonly known as Boyle's Law. Another relationship between P and V for an ideal gas which is more complex is for an isentropic process where

P*V^gamma=constant

where gamma is the specific heat ratio.
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• Member since:
June 24, 2006
Total points:
377 (Level 2)
mathematical relationship: PV = nRT
P = pressure (atmospheres)
V = volume (Liters)
n = # of moles
R = constant (0.08206)
T = temperature (Kelvin)

This equation is called the ideal gas law. You can see from it that when pressure goes UP, volume should go DOWN and vice versa. Hence, they are inversely proportional
• by waldon l
Member since:
October 03, 2006
Total points:
666 (Level 2)
They are inversely proportional. As pressure increases volume will decrease. For more specifics look up Boyle's law.
• 1 person rated this as good
• by Mech_Eng
Member since:
September 26, 2006
Total points:
2,319 (Level 3)
As pressure increases, volume decreases
( or as gas is being squeezed it is being force into a tighter space )
• by vijaya l
Member since:
May 25, 2006
Total points:
2,782 (Level 4)
Boyle's law-named for Robert Boyle-states that, at constant temperature, the pressure P of a gas varies inversely with its volume V, or PV = k, where k is a constant.

Charles's law-named for J.-A.-C. Charles (1746–1823)-states that, at constant pressure, the volume V of a gas is directly proportional to its absolute (Kelvin) temperature T, or V/T = k.

These two laws can be combined to form a single generalization of the behaviour of gases known as an equation of state,

PV = nRT,

where n is the number of gram-moles of a gas and R is called the universal gas constant. Though this law describes the behaviour of an ideal gas, it closely approximates the behaviour of real gases.

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• Member since:
October 04, 2006
Total points:
271 (Level 2)
Boyle's Law... At a constant temperature the volume of a given mass of gas is inversely proportional to its pressure.
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• by jekin
Member since:
September 18, 2006
Total points:
7,695 (Level 5)
If you reduce the volume by 1/2 you double the pressure after the temperature is reduced to where you started. I mean absolute pressure, not gage pressure. in other words the relationship is directly proportional, but you have to consider absolute temperature also. like 10-1 compression at sea level after cooling back is147 psi