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3

# Solubility Of Gases In Water

properties

7 replies to this topic
|

### #1 JPT@Victoria

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Posted 15 November 2019 - 02:32 PM

While performing some practice problems (it’s been a long time since I graduated as a chemical engineer, have not fully applied the knowledge over time so decided to review some concepts). I was looking for some material properties. Found the appendices of  “Ludwig's Applied Process Design for Chemical and Petrochemical Plants” 4th Edition” online.

Specifically at Appendix C, table C-16 “Solubility of Selected Gases in Water as a Function of

Temperature” The formula is not working for me. The resulting values are out of range. I’ve been looking online for possible things I may be doing wrong, but not successful. Also looked with no success for reference to check if there is an error in the formula or the correlation constants. The formula is: (T in K, I assume log10.)

log xwt = A + B/T + C log T + DT

(Have seen correlations that include a fifth correlation constant E times T^2)

Using the first material on the table to verify my results with the value provided at 25ºC

When I do the calculation, it returns an error because Log x = 2322.67, and 10^2322.67 is out or range.

I have found in other resources that the given x at 25C is correct (true for various of the substances given in this appendix C) so the formula, the constants, or my math are wrong!

Can someone provide some guidance?

Edited by JPT@Victoria, 15 November 2019 - 02:47 PM.

### #2 JPT@Victoria

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Posted 15 November 2019 - 02:48 PM

This is the formula and sample data:

### #3 breizh

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Posted 16 November 2019 - 12:11 AM

Hi ,

Did you check for other chemicals using the same correlation ?

https://www.engineer...ter-d_1148.html

https://sites.chem.c...es in water.pdf

Good luck

Breizh

Edited by breizh, 16 November 2019 - 12:32 AM.

### #4 JPT@Victoria

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Posted 18 November 2019 - 04:33 PM

Breizh,

To ease my quest for this puzzle, I have that appendix C-16 table copied in a spreadsheet, where I created the formula for the calculation. I have a file formatted in a way to enter substance and temperature with the spreadsheet returning the solubility.

The resulting value is an error. The solubility given in the appendix (it provides two values: at 25C and Tmax) are very close to the graphs on the Engineering Toolbox. Found that the values from the Genavtan document and the IUPAC documents are similar, however there is certain discrepancy from the sample values provided in this appendix C-16.

I did the same exercise in other tables of appencix C and all of them worked. It's only in this gas solubility table I got such errors. Was curious if I was incorrectly calculating it, but it looks like there is something wrong in the correlation variables, equiation, or else.

### #5 Nikolai T

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Posted 18 November 2019 - 09:05 PM

Hello,

What your gas is? What are conditions (T,P)? Why do you think values are out of range?

Regards,

Nikolai

### #6 breizh

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Posted 18 November 2019 - 11:29 PM

Hi JPT ,

thanks for the feedback .

Breizh

### #7 MrShorty

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Posted 19 November 2019 - 12:13 PM

If I understand, the equation + constants seems to work for other gases, but for Argon, it doesn't work. I would be inclined to compare the A, B, C, and D constants for the other gases and see how different they are -- maybe especially compare to O2, N2, or CH4, and see if the constants for Argon are similar to the constants for these other gases.

I notice in Briezh's CRC file that CH4 uses an equation in a similar form -- ln(x)=A+B/t+Cln(t)+Dt where t=T(K)/100. The constants for this equation given in the CRC link are -116, 156, 65, and -6.2. If I do the algebra to eliminate the divide by 100 (so the function is of T(K) only), I get A=-416, B=15600, C=65, and D=-0.062. In either case, these constants are quite different from what your source shows for Ar -- and Ar should not be orders of magnitude different from CH4.

In short, there seems to be something that doesn't match up between the given equation and the constants for that equation. I cannot readily see what is off, but something seems off.

### #8 Nikolai T

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Posted 20 November 2019 - 09:57 PM

Hello,

If I were you I would find another equestion and coefficients. Henry constant is mesured in pressure units. For solubility calculation you need to know composition of gas, pressure and temperature. I think the formula is not correct.

Regards,

Nikolai