[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*To*: "Bernd Ehret" <bernd.ehret@xxxxxxxxxxxxx>*Subject*: Re: bernd 050902*From*: "David L Parkhurst" <dlpark@xxxxxxxx>*Date*: Thu, 5 Sep 2002 08:33:29 -0600*Bcc*: "David L Parkhurst" <dlpark@xxxxxxxx>*In-reply-to*: <006d01c254cd$e04ee190$88042b8d@hydrologie.tucottbus.de>

I am pretty sure that PHREEQC is doing the calculation correctly in all cases. The problems you are solving are not equivalent. I just looked at case 1 and case 3 for comparison. Initially solutions 0, 1, 2, and 3 have volumes of 1 L. In case 1, you are taking .1 x 1 L of 0, .15 x 1 L of 1, .25 x 1 L of 2, and .5 x 1 L of 3 to make 1 L of 1001. However, in case 3, you are taking .072 x 1 L of 0, .108 x 1 L of 1, .180 x 1 L of 2, and .360 x 1 L of 3 to make .72 L of 1001. If you look at the results, the solution compositions of the mixture are the same in terms of molality. However, the next step causes a difference because solutions 0, 1, and 2 have 1 L of solution for both cases, but solution 1001 has 1 L for case 1 and .72 L for case 3. For the second mix in case 1, you add .1 x 1 L of solution 0, .2 x 1 L of solution 1, .3 x 1L of solution 2, and .4 x 1 L of solution 1001 to make 1 L of 1002. For case 3, you add .072 x 1 L of solution 0, .144 x 1 L of solution 1, .216 x 1 L of solution 2, and (here is the difference) .288 x .72 L of solution 1001 to make .6394 L of solution 1002. The proportion of 1001 in 1002 is different between the two cases .4x1/1 = .4 for case 1 and .288x.72/.6394 = .32 for case 3. I don't know which you want. Case 3 will give a constantly diminishing volume of water; case 2 will eventually give a huge volume of water; so I think you probably want to scale things correctly to keep a constant volume of water. David David Parkhurst (dlpark@xxxxxxxx) U.S. Geological Survey Box 25046, MS 413 Denver Federal Center Denver, CO 80225 Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled

**References**:**Re: bernd 050902-2***From:*Bernd Ehret

- Prev by Date:
**Re: bernd 050902-2** - Next by Date:
**Re: non-convergence** - Previous by thread:
**Re: bernd 050902-2** - Next by thread:
**O2(g) Minteq** - Index(es):

Project Home Page

Complete Water Resources Division Software

USGS Home Page

Water Resources Division Home Page

NRP Home Page

Help Page

Please note that some U.S. Geological Survey (USGS) information accessed through this page may be preliminary in nature and presented prior to final review and approval by the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user.

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.

The URL of this page is:
https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/mail/msg00060.html

Email:dlpark@usgs.gov

Last modified: $Date: 2005-09-13 21:04:21 -0600 (Tue, 13 Sep 2005) $

Visitor number 1973 since Jan 22, 1998.