Compressibility of liquid vs solid actual numbers

[fahraynk]

I was trying to find the compressibility of water and compressibility of air to compare.
For compressibility of water I found 46.4e-6
For compressibility of a gas... I am having a tough time finding anything. compressibility factor I can find, which is 1 for Hydrogen... but how does that relate to compressibility?

Also... if a liquid is much more viscous than water... water is .001[Pa*sec] so say if the viscosity = 2 then would it likely be more or less compressible than water?

 

[DrClaude]

For compressibility of a gas... I am having a tough time finding anything. compressibility factor I can find, which is 1 for Hydrogen... but how does that relate to compressibility?

That is the compresibility, which for an ideal gas is exactly 1, and real gases have k ≈ 1.

Also... if a liquid is much more viscous than water... water is .001[Pa*sec] so say viscosity = 2... then would it likely be more or less compressible than water?

I will let more knowledgeable people answer, but I would be surprised if there was a link between compressibility and viscosity.

 

[Chestermiller]

That is the compresibility, which for an ideal gas is exactly 1, and real gases have k ≈ 1.

Hi DrClaude,
From the value he give for liquid water, I don't think he was referring to the compressibility factor z. I think he was referring to the reciprocal of the bulk modulus. For an ideal gas, the compressibility is equal to 1/p. For liquid water, it looks like the value he gave has units of 1/kPa.

I will let more knowledgeable people answer, but I would be surprised if there was a link between compressibility and viscosity.

I agree with your assessment.

 

[DrClaude]

Hi DrClaude,
From the value he give for liquid water, I don't think he was referring to the compressibility factor z. I think he was referring to the reciprocal of the bulk modulus. For an ideal gas, the compressibility is equal to 1/p. For liquid water, it looks like the value he gave has units of 1/kPa.

Thanks for the clarification.

 

[fahraynk]

From Fundamentals of aerodynamics John D Anderson :
Compressibility Φ :
$$\phi = \frac{1}{\rho}\frac{d\rho}{dP}$$
$$dP=\rho\phi d\rho$$

He derives this by manipulating this equation : $$\phi=\frac{1}{v}\frac{dv}{dP}$$ where v is specific volume = 1/ρ

Also I got the compressibility of water from this source : http://hydrogen.physik.uni-wuppertal.de/hyperphysics/hyperphysics/hbase/tables/compress.html

 

[Chestermiller]

From Fundamentals of aerodynamics John D Anderson :
Compressibility Φ :
$$\phi = \frac{1}{\rho}\frac{d\rho}{dP}$$
$$dP=\rho\phi d\rho$$

He derives this by manipulating this equation : $$\phi=\frac{1}{v}\frac{dv}{dP}$$ where v is specific volume = 1/ρ

Also I got the compressibility of water from this source : http://hydrogen.physik.uni-wuppertal.de/hyperphysics/hyperphysics/hbase/tables/compress.html

If you apply this to an ideal gas, you get a compressibility of 1/P.

 

[fahraynk]

If you apply this to an ideal gas, you get a compressibility of 1/P.

So, am I right to say that 1/(46.4e-6), water is 21551 times less compressible than an ideal gas? (at a pressure of 1atm)

 

[Chestermiller]

So, am I right to say that 1/(46.4e-6), water is 21551 times less compressible than an ideal gas? (at a pressure of 1atm)

No. The comparison depends on the pressure. In the case of liquid water, the compressibility is very insensitive to pressure. In the case of an ideal gas, the compressibility is sensitive to the pressure. So you have to specify at which pressure you are making the comparison.

 

[fahraynk]

No. The comparison depends on the pressure. In the case of liquid water, the compressibility is very insensitive to pressure. In the case of an ideal gas, the compressibility is sensitive to the pressure. So you have to specify at which pressure you are making the comparison.

1 atm.
The compressibility on this site if I am reading it correctly (I might not be) says 46.4e-6 at 1atm http://hydrogen.physik.uni-wuppertal.de/hyperphysics/hyperphysics/hbase/tables/compress.html
The compressibility of ideal gas, 1/P... is that pressure in atmospheres? Because then the compressibility at 1atm = 1, and 1/46.4e-6 = 21551

 

[Chestermiller]

1 atm.
The compressibility on this site if I am reading it correctly (I might not be) says 46.4e-6 at 1atm http://hydrogen.physik.uni-wuppertal.de/hyperphysics/hyperphysics/hbase/tables/compress.html
The compressibility of ideal gas, 1/P... is that pressure in atmospheres? Because then the compressibility at 1atm = 1, and 1/46.4e-6 = 21551

If the compressibility of the liquid water is 46.4E-4/atm (i.e., the pressure unit used for the pressure change is atm.), then I agree with this comparison.