Pressure vs. Size of Particles [closed]








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If two containers with different sized particles are held at the same temperature, which gas will exert more pressure?




The ideal gas law assumes that gas molecules are point particles, so regardless of how big the molecule actually is, if you have the same number of molecules at the same temperature contained within the same volume, the pressure will be the same.


If you incorporate the modifications that the van der Waals equation introduces, where molecular size and intermolecular forces are taken into account, then the pressure goes up as the size of the molecule increases. We can see this by rearranging the van der Waals equation to solve for the pressure $P$:
$$
P = \frac{RT}{V/n - b} - a\left(\frac{n}{V}\right)^2
$$
where $T$ is the temperature, $V$ is the volume, $n$ is the number of molecules, $R$ is the gas constant, and $a$ and $b$ depend on the identity of the gas where $a$ accounts for intermolecular forces and $b$ accounts for the molecular size. Thus, we care mostly about $b$, though of course the size of the molecule changes $a$ as well. From the equation, we can see that, all else held equal, if $b$ increases (i.e. the molecule size increases) then the pressure goes up.


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