Why Is Acetone's Pressure Relevant in Determining Air Pressure in a Tank?

[Mark Gerts]

Homework Statement

I guess the way but I'm blind to the solution

Relevant Equations

All I see here are the equlations of absolute and extended pressure (P abs = P atm + P ext), so the temperature, liquid height and 2 different pressures need seem odd, but they must be used

Can you, please, help me with this exercise? I know the formulas for the required parameters, but I know neither how to use them here nor in what way to solve the exercise. Plus I don't understand what for I was given the temperature
Thank you for your help and advice

 

[Chestermiller]

Homework Statement:: I guess the way but I'm blind to the solution
Relevant Equations:: All I see here are the equlations of absolute and extended pressure (P abs = P atm + P ext), so the temperature, liquid height and 2 different pressures need seem odd, but they must be used

Can you, please, help me with this exercise? I know the formulas for the required parameters, but I know neither how to use them here nor in what way to solve the exercise. Plus I don't understand what for I was given the temperature
Thank you for your help and advice

What is the exact word-for-word statement of the problem?

 

[Mark Gerts]

What is the exact word-for-word statement of the problem?

What absolute and exceeded pressure should be created in the air pipe to create gas bubbles in the liquid?

 

[Chestermiller]

What absolute and exceeded pressure should be created in the air pipe to create gas bubbles in the liquid?

What is the definition of exceeded pressure? I have never heard the term before.

 

[Mark Gerts]

What is the definition of exceeded pressure? I have never heard the term before.

I'm sorry, maybe my translation wasn't correct. That's the pressure of the substance on the environment or vessel excluding the atmospheric pressure

 

[Lnewqban]

I believe the temperature is given, so you can calculate the density of the liquid inside the tank and the pressure it produces at the point the hose discharges.
Please, see:
https://www.engineeringtoolbox.com/...cific-weight-temperature-pressure-d_2038.html

 

[Mark Gerts]

I believe the temperature is given, so you can calculate the density of the liquid inside the tank and the pressure it produces at the point the hose discharges.
Please, see:
https://www.engineeringtoolbox.com/...cific-weight-temperature-pressure-d_2038.html

I see, but why do I need acetone's pressure if I'm given the pressure inside the tank? And how to use this information to find out the necessary absolute pressure of the air?

 

[Chestermiller]

By extended pressure, I think that means the gauge pressure.

If $p_{atm}$ is the atmospheric pressure at the upper surface of the acetone, $\rho$ is the density of the acetone, and h is the depth at which the bubbles form, what is the absolute pressure p at depth h?

This being the case, what does the pressure inside a forming bubble have to be in order for the bubble to form and grow?

What does that tell you about the pressure in the air hose releasing the bubble?

 

[Lnewqban]

I see, but why do I need acetone's pressure if I'm given the pressure inside the tank? And how to use this information to find out the necessary absolute pressure of the air?

You only know the manometric pressure above the surface of the liquid, which has been given as $P_{m2}$.
That pressure is not the same for all the points inside the tank, as it happens to a diver in the ocean, as you dive deeper into the liquid, your ears feel increased static pressure.

Please, see:
https://en.wikipedia.org/wiki/Hydrostatics#Hydrostatic_pressure

Note that the value of manometric pressure is always respect to absolute atmospheric pressure.
A manometer that is not connected to anything will indicare zero, even when it is under the effect of the absolute atmospheric pressure.