Air in Mercury & Sprengel Pump Explained

In summary, the sprengel pump uses falling mercury to trap air and evacuate a chamber. Despite the air trying to rise back up, the small diameter of the capillary tube and the large surface tension of mercury prevent it from escaping. It would be difficult to use another fluid besides mercury due to its high density and non-wetting properties. This process is also influenced by the coulomb force.
  • #1
cragar
2,552
3
I was reading about the sprengel pump , And it uses falling mercury to trap air to evacuate a chamber to get the air out of it , http://en.wikipedia.org/wiki/Sprengel_pump you can look at the diagram of the pump , my question is when the mercury traps the air and pushes it down , why doesn't the air just rise back to the top like air bubbles coming out of a divers mask back to the surface of the ocean.
 
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  • #2
It tries, but the diameter of the capillary tube is so small, and mercury surface tension so large, that air is trapped. It is just a matter of equilibrium of forces involved.
 
  • #3
sweet thanks for the answer , is there any other fluid that i could use besides mercury so that i could make my own , so this has a lot to do with the coulomb force.
 
  • #4
Will be difficult. Mercury is very good for two reasons - it has a very high density (hence can "suck" air much stronger than lighter liquids) and doesn't wet glass surface (which means it can't flow around the bubble on the glass walls).
 
  • #5


This is a great question! The key difference between the air bubbles rising to the surface of the ocean and the air being trapped by the mercury in the sprengel pump is the force of gravity. In the ocean, the air bubbles rise to the surface because they are less dense than the surrounding water and are pushed upwards by the force of gravity. However, in the sprengel pump, the air is being trapped by the mercury, which is much more dense than air and therefore exerts a greater force of gravity. This force of gravity is strong enough to keep the air trapped at the bottom of the pump, even as the mercury continues to fall and create a vacuum above it. So, while it may seem counterintuitive, the force of gravity is actually what keeps the air trapped at the bottom of the pump and prevents it from rising back to the top.
 

1. What is the composition of air in Mercury?

The air in Mercury is primarily made up of oxygen, nitrogen, and trace amounts of other gases such as argon, carbon dioxide, and water vapor.

2. How does the air in Mercury differ from Earth's atmosphere?

The air in Mercury is much thinner than Earth's atmosphere, as Mercury has a weaker gravitational pull. It also lacks a significant magnetic field, resulting in a lack of protection from solar winds and radiation.

3. How is the air in Mercury affected by its proximity to the sun?

The extreme temperatures in Mercury's atmosphere, ranging from -290°F to 800°F, cause the gases in the air to constantly escape into space. Additionally, solar winds can strip away parts of the atmosphere.

4. What is a Sprengel pump and how does it work?

A Sprengel pump is a type of vacuum pump that uses mercury to create a vacuum. It involves a vertical tube filled with mercury that is connected to a reservoir of mercury and a vacuum chamber. The difference in mercury levels creates a pressure difference that pulls air out of the vacuum chamber.

5. How is a Sprengel pump used in scientific experiments?

A Sprengel pump is commonly used in scientific experiments that require a vacuum, such as in chemistry or physics. It is also used in the production of vacuum tubes and in the production of semiconductors. It can create a vacuum up to 0.001 torr, making it suitable for a wide range of experiments and applications.

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