Balloon Experiment - Understanding Pressure & Volume On Different Processes

Summary

This video explores the relationship between pressure and volume through two balloon-in-chamber setups. In the first, a sealed balloon expands as gas is pumped out, lowering pressure inside both the chamber and the balloon. The pressure reduction can be measured by the balloon's expansion. In the second setup, the balloon is connected to atmospheric pressure, allowing air to flow back in as the chamber's pressure drops. This keeps the balloon's pressure equal to atmospheric pressure. The experiment highlights how vacuum pumps must be selected based on the pressure changes and air flow in each scenario.

Takeaways

• 😀 The relationship between pressure and volume can be understood through the behavior of a balloon in a chamber.
• 😀 In the first setup, the balloon is sealed inside a chamber at atmospheric pressure, and when gas is pumped out, the pressure inside the chamber and the balloon decreases.
• 😀 As the gas is pumped out, the remaining molecules spread out to fill the volume, reducing the pressure.
• 😀 Since the balloon is not a pressure vessel, the pressure inside and around it is always the same, meaning both pressures equalize.
• 😀 If the balloon doubles in size, the pressure inside and around it would be half of atmospheric pressure.
• 😀 The vacuum pump for this setup must be chosen based on its ability to reach the required pressure in a given timeframe.
• 😀 In the second setup, the balloon's mouth is connected to atmospheric pressure outside the chamber, allowing air to flow into the balloon.
• 😀 When the chamber is evacuated, the balloon still expands, but the pressure inside the chamber remains close to atmospheric pressure due to the continuous air flow into the balloon.
• 😀 The pressure in the chamber is slightly reduced when gas is pumped out, but the balloon continues to expand as air from the outside is drawn into it.
• 😀 In this setup, the pump needs to be sized to handle the constant flow of air entering from the atmosphere.

Q & A

What happens to the gas inside the balloon when gas is pumped out of the chamber?

When gas is pumped out of the chamber, the remaining molecules in the balloon spread out to fill the available space, causing the balloon to expand.

How does the pressure inside the chamber change when gas is pumped out?

As gas is pumped out of the chamber, the pressure inside the chamber decreases because there are fewer gas molecules, leading to a reduction in pressure.

Is the balloon a pressure vessel in this setup?

No, the balloon is not a pressure vessel. The pressure inside the balloon and the chamber is always the same.

What does it mean if the balloon expands to twice its original size?

If the balloon expands to twice its original size, the pressure around it has reduced to half of the atmospheric pressure.

How should the vacuum pump be selected for this setup?

The vacuum pump should be selected based on its ability to achieve the desired pressure reduction within a specified timeframe.

What is different about the second setup involving atmospheric pressure outside the chamber?

In the second setup, the balloon is connected to atmospheric pressure outside the chamber. As the chamber is evacuated, air is drawn back into the balloon, which prevents the pressure inside the balloon from dropping below atmospheric pressure.

What happens to the pressure in the chamber when the balloon is connected to atmospheric pressure outside the chamber?

The pressure in the chamber is slightly reduced as gas is pumped out, but the pressure inside the balloon equalizes with atmospheric pressure due to the connection to the outside atmosphere.

How does air flow into the balloon in the second setup?

Air flows into the balloon through the connection to the atmosphere as the pressure in the chamber decreases.

What is the significance of atmospheric pressure in the second setup?

Atmospheric pressure is the reference pressure in the second setup, and it ensures that the pressure inside the balloon remains constant at atmospheric pressure throughout the experiment.

How does the vacuum pump need to be sized in the second setup?

In the second setup, the vacuum pump must be sized based on the constant flow of air coming into the balloon at atmospheric pressure, rather than just evacuating gas from the chamber.