If the pressure on a gas increases, does the volume of the gas also increase?

Question

Mateo Aguilar · Accepted Answer

Maybe, maybe not.

As #PV = nRT# for ideal gases, if #P# increases, then #V# must decrease, if nothing is held constant. Otherwise one side of the equality increases while the other does not, which disobeys mathematics.

If the gas is in a closed rigid container, and it already spreaded out to fill the entire container, then if pressure increases (for instance, by adding more of the same gas), its temperature can increase.

This would be then, an example of constant-volume (isovolumetric/isochoric) compression. From the ideal gas law:

#VDeltaP = RDelta(nT)#

or #P_1V = P_2V = n_1RT_1 = n_2RT_2#

or #(P_1)/(n_1T_1) = (P_2)/(n_2T_2)#

If pressure increases, #DeltaP > 0#. Since volume and mols are always positive, #DeltaT > 0# as well, meaning that the container gets hotter.

Again, this would occur when the volume is held constant, which is quite feasible. In this case, the volume of the gas, again, would not change.

Natalie Anton · Answer

If the pressure on the gas increases, the volume of the gas does not increase. Instead, the volume decreases.

The general equation of ideal gases is PV = nRT.......................................... (1). Since the volume "V" is inversely proportional to the pressure "P," an increase in pressure "P" will result in a decrease in volume "V," equation (1) can be reduced to PV = constant................................................. (2) for a given quantity of the gas (n = constant) and temperature (T = constant). Respectfully, Dr. Mamdouh Younes Hamilton, Ontario, Canada

Luna Chen · Answer

undefined No, if the pressure on a gas increases, the volume of the gas decreases, provided that the temperature remains constant. This relationship is described by Boyle's Law.