B Why Does Mercury Enter Water in Andrews' CO2 Experiment?

[akashpandey]

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.

 

[DrClaude]

Do you mean why does the mercury not fall down to be replaced by water?

 

[akashpandey]

Yes.

 

[DrClaude]

Because water can not slip past the mercury to go up the tube, and inversion is not possible. It is a metastable situation.

 

[akashpandey]

Can you give this explanation in more accurate way ( mathematical way) cause i didnt understand this yet.
Plz

 

[akashpandey]

I am still confuse because densities are different so water should slip past the mercury.

 

[DrClaude]

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.

 

[akashpandey]

What about gravity acting on mercury.
SO it has to in liquid

 

[DrClaude]

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.)

 

[akashpandey]

Thank you