Jump to content

[OLD] Negative concentrations


webmaster
 Share

Recommended Posts

From: Henry Kerfoot

Subject: negative concentrations

When I use the following parameters for reaction of feldspars with groundwater, I get results with [H+] 0. Is this an indication of instability due to use of too large a reaction step, or some other type of effect? I also occasionally get [O2] 0, which I assume is a reflection of the same thing.... Has anyone had experience with these types of issues? Here is the input and system information ....

Basis is: H2O

1 kg solvent

NO3- (swapped for

NH3(aq)) total mg/l = .4

Na+ total mg/l = 8.4

K+ total mg/l = 3.5

Ca++ total mg/l = 13

Mg++ total mg/l = 4.3

Fe++ total mg/l = .18

HCO3- total mg/l = 72

SO4-- total mg/l = 6.9

Cl- total mg/l = 3.8 (

F- total mg/l = .2

SiO2(aq) total mg/l = 35

H+ pH = 7

O2(aq) total mg/l = 4

Al+++ total mg/l = .1

Mn++ activity = 1e-12

Zn++ total mg/l = .09

HPO4-- total mg/l = .1

show reactants

Reactants:

React .05 mol of K-Feldspar

React .05 mol of Albite

show variables

Variables set by user:

cpw = 1 cal/g C

cpr = .2 cal/g C

delxi = .01

density = 1 g/cm3

dxplot = .005

dxprint = .1

epsilon = 5e-11

inert = 0 cm3

itmax = 400 iterations

itmax0 = 999 iterations

nswap = 30 iterations

nswap0 = 200 iterations

simax = 3 molal

TDS = 148 mg/kg

theta = .6

timax = 3 molal

 

From: Craig Bethke

Subject: RE: negative concentrations

I think you are confusing the concentration of a species in solution with that of a component. Whereas the concentration of a species is invariably a positive number, a component's concentration may be positive or negative. There's a section in the green book titled “Components with Negative Masses�, on page 38. If you read this (and perhaps the preceding pages, starting on page 30), I think this point will be clear.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...