(a) A real gas is introduced into a flask of volume \(V\). Is the corrected volume of the gas greater or less than \(V ?\) (b) Ammonia has a larger \(a\) value than neon does (see Table 5.4 ). What can you conclude about the relative strength of the attractive forces between molecules of ammonia and between atoms of neon?

When we discuss the behavior of gases, it's common to start with the Ideal Gas Law, which is a simplified model assuming no intermolecular forces and that the gas particles have negligible volume. However, real gases do not always adhere to this model because their molecules do exhibit volume and attractions.

This is where the 'corrected volume' comes into play. In the context of the van der Waals equation, which is used to describe the behavior of real gases more accurately, the volume 'V' of the flask is not the actual volume the gas molecules have available to move around in. The molecules themselves occupy space, so the volume available for the gas's motion (the 'corrected volume') is indeed less than the flask's volume. The van der Waals equation accounts for this by subtracting a term related to the volume of the gas particles from the volume of the container.

The equation recognizes that the particles of a real gas have finite volume and that this volume reduces the space in which the gas can exert pressure. By adjusting the volume in this way, the equation offers a more accurate description of the behavior of a real gas under various conditions.

Intermolecular forces are the attractions or repulsions that occur between molecules. They are crucial for understanding the properties of substances, including gases. In the van der Waals equation, the constant 'a' provides an adjustment for the attractive forces between gas particles.

The magnitude of 'a' reflects how strongly the particles of a gas attract each other. A higher 'a' value indicates stronger intermolecular attractions, which can lead to deviations from ideal gas behavior. These forces are especially significant under the conditions of high pressure and low temperature, where gases are more likely to deviate from ideal behavior.

In essence, stronger intermolecular forces can lead to a reduced volume (as particles are pulled closer together) and an increase in the boiling point of a substance. An understanding of these forces offers valuable insight into why gases condense into liquids at different temperatures and why their volumes deviate from the ideal model under various conditions.

Comparing the properties of ammonia (NH₃) and neon (Ne), we find significant differences due to their distinct structures and intermolecular forces. Ammonia is a polar molecule with a significant dipole moment, while neon is a noble gas with a symmetrical electronic structure leading to no permanent dipole.

Ammonia's larger 'a' value in the van der Waals equation indicates that its molecules experience stronger attractive forces than those between neon atoms. These forces in ammonia arise mainly from hydrogen bonds and dipole-dipole interactions, which are absent in neon as it is monoatomic. This difference in intermolecular attractions results in ammonia having a higher boiling point and a tendency to deviate more from ideal gas behavior compared to neon.

Moreover, the presence of such attractive forces makes ammonia more likely to liquefy under compression than neon, which requires substantially lower temperatures or higher pressures to do so. Understanding these distinctions helps explain the varied physical behavior of these gases under the same conditions.