Why Doesn't Decreasing Volume Increase Molecular Speed According to Boyle's Law?

In summary, the conversation discusses the relationship between volume and pressure according to Boyles Law. It is stated that when volume is decreased, pressure increases due to the rate of change of momentum. However, it is also mentioned that there is no increase in average molecular speed because the density increases when volume decreases, resulting in more particles imparting momentum to the container walls. This can be seen in the equation for pressure, where density increases as volume decreases.
  • #1
Kajan thana
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18
Hi guys,
From Boyles Law, we know that Volume is inversely proportional to Pressure give that the temperature is kept.
My question, if we decrease the volume, the pressure will increase due to rate of change of momentum ( we can say those two are proportional), then why can we not claim that there is increase in average molecular speed?
 
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  • #2
The reason the pressure goes up for the same temperature (and same average molecular speed) is that the density is increased when you decrease the volume. Thereby, you have more particles per given time imparting momentum to the walls of the container. ## P=\frac{n}{V} RT ## . Notice the density ## \frac{n}{V} ## has increased as you decrease ## V ##.
 
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Related to Why Doesn't Decreasing Volume Increase Molecular Speed According to Boyle's Law?

What is Boyle's Law?

Boyle's Law is a fundamental gas law that describes the relationship between the pressure and volume of a gas at a constant temperature. It states that the pressure of a gas is inversely proportional to its volume, meaning that as the volume of a gas decreases, its pressure increases and vice versa.

What is the formula for Boyle's Law?

The formula for Boyle's Law is P1V1 = P2V2, where P1 and V1 represent the initial pressure and volume, and P2 and V2 represent the final pressure and volume. This formula can also be written as P1/P2 = V2/V1.

What is the significance of Boyle's Law?

Boyle's Law is significant because it helps us understand the behavior of gases under different conditions. It is used in many real-world applications, such as in scuba diving, where changes in pressure affect the volume of air in a diver's tank, and in the compression of gases in engines.

How does thermal physics relate to Boyle's Law?

Thermal physics is the study of the relationship between heat, temperature, and energy. Boyle's Law is a part of thermal physics because it explains the behavior of gases when heat is added or removed. As the temperature of a gas changes, its volume and pressure also change according to Boyle's Law.

What are some real-world examples of Boyle's Law?

Boyle's Law can be observed in many everyday situations, such as inflating a balloon, using a bike pump, or filling a tire with air. It is also used in medical applications, such as in oxygen tanks, where the gas is compressed to increase the amount of oxygen that can be stored in a smaller volume.

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