Video: Applying Knowledge of the Behavior of Gas Molecules

For statements I and II, state for each if they are true or false. I) In the kinetic theory of gases, collisions between gas particles and the walls of the container are considered inelastic. II) Gas molecules have strong intermolecular forces and move in regular patterns. If both are true, state if II is a correct explanation for I.

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Video Transcript

For statements I and II, state for each if they are true or false. I) In the kinetic theory of gases, collisions between gas particles and the walls of the container are considered inelastic. II) Gas molecules have strong intermolecular forces and move in regular patterns. If both are true, state if II is a correct explanation for I.

The kinetic theory of gases is a model that’s used to account for the macroscopic properties of gases, such as the gas’s pressure, its volume, or its temperature at the level of individual gas particles like molecules or atoms. The kinetic theory of gases was developed because scientists had discovered a number of laws through experimentation that dictated gas behaviors, such as these gas laws. Those scientists had observed gases behaving according to these laws over and over again. They fundamentally didn’t understand what was going on inside a container of gas that made all of these laws true. Scientists also had a number of fundamental questions that they hoped to answer by developing this model.

For example, pressure is a measure of the force exerted on a surface. We know that a container of gas has a pressure. So the gas must be exerting some kind of force on the container. So how do gas particles create this force? Scientists also wanted to know what exactly temperature was measuring at the level of gas particles. The kinetic theory of gases is based on a number of assumptions.

The first assumption is that a gas consists of a huge number of particles that are incredibly small compared to the volume of the container. This means that there will be a lot of empty space in between each gas particle. The second assumption is that these gas particles are in constant random motion. And they’re frequently colliding with each other and the walls of the container. The third assumption is that between collisions, the particles don’t interact with each other. They’re not attracted to each other. And they also don’t repel each other.

Our fourth and final assumption is that when these gas particles do collide, the collisions are elastic. In an elastic collision, there’s no loss of kinetic energy. An elastic collision is what you see when you see two billiard balls or two ping pong balls hitting each other. The balls move towards each other, hit each other, and then move away. One ball might slow down and one ball might speed up. But between the two balls, there’s no change in their total kinetic energy. You don’t see two ping pong balls or billiard balls move towards each other and then stick together and not move anymore. Which indicates that they lost their kinetic energy. That would be an example of an inelastic collision.

Now that we understand a little bit about how gases behave at the level of individual particles. And we understand some of the assumptions behind the kinetic theory of gases. Let’s return to the question. Statement I says that in the kinetic theory of gases, collisions between gas particles and the walls of the container are considered inelastic. As we’ve just discussed, one of the assumptions in the kinetic theory of gases is that when gas particles collide with each other or with the walls of the container, those collisions are elastic, not inelastic. So statement I is false.

Statement II says that gas molecules have strong intermolecular forces and move in regular patterns. One of the assumptions of the kinetic theory of gases is that gas particles are in constant random motion. They don’t move in regular patterns. Intermolecular forces are attractions that occur between particles. However, particles of ideal gases don’t interact with each other. So there’s no intermolecular forces between them. Since gas particles don’t have strong intermolecular forces. And they don’t move in regular patterns. Statement II is false. Since statement I and II are both false, we don’t have to state if II is a correct explanation for I.

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