Why Does Mercury Enter Water in Andrews' CO2 Experiment?

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Discussion Overview

The discussion revolves around the behavior of mercury in water during Andrews' CO2 experiment, specifically addressing why mercury does not simply fall and allow water to replace it, despite the differences in density between the two liquids.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why mercury does not fall down to be replaced by water, given that mercury is denser than water.
  • Another participant suggests that water cannot slip past the mercury to rise in the tube, describing the situation as metastable.
  • A request is made for a more accurate mathematical explanation of the phenomenon.
  • Some participants express confusion about the implications of density differences, suggesting that water should be able to slip past the mercury.
  • It is noted that the surface tension of mercury prevents bubbles of water from forming within it, complicating the interaction between the two liquids.
  • Gravity's role in the behavior of mercury is acknowledged, with one participant providing an analogy involving a bottle of water to illustrate the dynamics of liquid movement and air displacement.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and confusion regarding the interaction between mercury and water, indicating that multiple competing views remain and the discussion is unresolved.

Contextual Notes

Some participants highlight limitations in their understanding of the underlying principles, particularly regarding the mathematical and physical explanations of the observed behavior.

akashpandey
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Why mercury go inside the water in andrews experiment.
Because as we know density of mercury is greater than water so why mercury go inside the water in andrews experiment on co2.
 
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Do you mean why does the mercury not fall down to be replaced by water?
 
Yes.
 
Because water can not slip past the mercury to go up the tube, and inversion is not possible. It is a metastable situation.
 
Can you give this explanation in more accurate way ( mathematical way) cause i didnt understand this yet.
Plz
 
I am still confuse because densities are different so water should slip past the mercury.
 
akashpandey said:
I am still confuse because densities are different so water should slip past the mercury.
It physically can't insert itself between the mercury and the glass of the tube and the surface tension of mercury is too strong for bubbles of water to form inside the mercury.
 
What about gravity acting on mercury.
SO it has to in liquid
 
Of course that gravity is pulling on the mercury.

Do this experiment: take a big 2l bottle and fill it to the brim with water. Now turn it upside down very quickly. You will see that the water will have a hard time coming out, and the air going in, making the water come out in pulses. This is because to get water out, air has to take water's place, and the only way it can do that is by bubbling up through the water, which takes time. With water and mercury, the situation is so much worse that it is metastable: water will not be able to bubble up to the top of the mercury column, and the liquids stay in place.

(While you are making the experiments with the bottle of water, try this: after turning it upside-down, make a quick circular motion horizontally, to create a whirlpool of water inside the bottle. You will see that the water now flows out very smoothly. This is because the whirlpool creates a "hole" in the middle of the water and air can easily flow in.)
 
  • #10
Thank you
 

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