Question

As the velocity of molecules increases the number of collisions per unit time (1) decreases (2) increases (3) does not change (4) none

Short answer

The number of collisions per unit time increases.

Step-by-step solution

- Understanding Kinetic Theory

In the kinetic theory of gases, the velocity of gas molecules is directly related to their kinetic energy. As temperature increases, so does the kinetic energy, leading to higher velocities.

- Relating Velocity to Collisions

Higher velocity means that molecules are moving faster within a given volume of gas. Faster movement results in molecules covering more distance in a shorter amount of time.

- Effect on Collisions per Unit Time

Since molecules are moving faster, the likelihood of them colliding with each other in a given period increases. Therefore, the number of collisions per unit time will also increase.

- Conclusion

Based on the above points, as the velocity of molecules increases, the number of collisions per unit time also increases.

Key concepts

Molecular Velocity

The kinetic theory of gases helps us understand how molecules move and interact in a gas.
One important part of this theory is molecular velocity.
Molecular velocity refers to the speed at which gas molecules move.
It is directly related to kinetic energy, which is the energy a molecule has due to its motion.
According to the kinetic theory, as you increase the temperature, the kinetic energy of the gas molecules also increases.
This means that the molecules will move faster, hence the term molecular velocity.

Higher molecular velocities mean that the molecules are covering more distance in a shorter time, leading to more dynamic behavior within the gas. This concept is critical for understanding various properties of gases, including pressure, volume, and temperature.

Collision Frequency

Collision frequency refers to how often gas molecules collide with each other within a given period.
When molecules move faster, there's a higher chance they will bump into each other more frequently.
This is because faster-moving molecules traverse the space in the gas more quickly, leading to more encounters.

So, if the molecular velocity increases, the collision frequency also goes up.
Imagine a crowded room where people are walking around slowly.
They’ll occasionally bump into each other.
Now, if everyone starts running, there will be more frequent collisions.
That’s similar to what happens in a gas when its molecules gain speed.

Higher collision frequency affects properties like the rate of chemical reactions within the gas, as more frequent collisions make reactions more likely.

Temperature Effects

Temperature is a measure of the average kinetic energy of molecules in a substance.
In a gas, as the temperature increases, the kinetic energy of the molecules also increases.
This causes the molecules to move faster.

An increase in temperature thus leads to higher molecular velocities and more frequent collisions.
That's why hot gases tend to expand, as the fast-moving molecules spread out.

The relationship can be summarized as follows:

• Higher Temperature → Higher Kinetic Energy
• Higher Kinetic Energy → Higher Molecular Velocity
• Higher Molecular Velocity → Higher Collision Frequency

Understanding these effects can help us grasp why gases behave differently under various temperature conditions.

For example, in everyday life, when you heat up the air inside a balloon, the balloon expands.
The reason for this is that the increased temperature accelerates the gas molecules, causing them to collide more often and pushing the balloon’s walls outward.