# Re: bernd 14-11-01

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The REACTION data block is an independent definition that does not use
information from RATES or KINETICS. REACTION simply specifies a number of
moles of reactants to be added to a solution. In your example, REACTION
would add .001 mole Ca, 0.001 + 2*.001*55.5 mole H, and .001*55.5 mole O to
solution 9. However, you should use the formula Ca(OH)2 to have a charge
balanced reactant. Normally, I would not add the water with REACTION. If it
is a mixing of solutions, I would define two solutions and use the MIX data
block.

KINETICS requires a corresponding RATES definition. The reaction that is
added is defined with the -formula identifier in KINETICS and the rate
expression is defined in RATES. The rate expression is defined once in
RATES, but could be used by multiple KINETIC data blocks. You are adding
your reaction twice by including both KINETICS and REACTION.I do not
include the water in the reaction. You are removing reactants with a
negative number of moles, which would imply you are removing water from the
system. I don't think this is what you want to do. The rate expression
indicates you will remove all alkalinity by precipitating Ca(OH)2, which
does not make much physical sense. You will run into a problem if there is
not enough calcium to balance the alkalinity. I have not run this because I
think there are too many conceptual problems, but the following at least
shows the basic connection between RATES and KINETICS.

RATES
Ca(OH)2
-start
1 rem M = current number of moles of Ca(OH)2
2 rem M0 = number of moles of Ca(OH)2 initially present
10  if (pH >= 6.0) then goto 200
15  M = - ALK*0.5
20  rate = M
30  moles = rate * TIME
200 SAVE moles
-end
END
KINETICS 1
Ca(OH)2
-formula           Ca(OH)2  1.0
#         -m0 0.0
#         -m  0.0                     #MOL("CaOH")
END
USE solution 9
USE kinetics 1
END

David

David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225

"Bernd Ehret"
<ehbernd@xxxxxx>         To:      "David L Parkhurst" <dlpark@xxxxxxxx>
cc:
11/14/01 01:03           Subject: Re: bernd 14-11-01
AM

In the file above I send you my problem with RATES in connection with
KINETICS or REACTION:
In RATES I want to use the value of alkalinity (negative ALK) to produce
moles for the KINETICS or REACTION. Specially in the lines ...
...
RATES
CaOH
-start
1 rem M = current number of moles of calcite
2 rem M0 = number of moles of calcite initially present
10  if (pH >= 6.0) then goto 200
15  M = - ALK
20  rate = M
30  moles = rate * TIME
200 SAVE moles
-end
END
REACTION 1
CaOH(H2O)55.5 1.0
??? mmol                     #??? How come the moles from RATES to
KINETICS
or REACTION?
END

KINETICS 1
CaOH  1.0
H2O  55.5
# -m0 0.0
# -m  0.0   #MOL("CaOH")
END

How come the moles from RATES to KINETICS or REACTION?
And I don't understand the right connection between moles in RATES and
moles in KINETICS or REACTION.
Bernd(See attached file: CaOH_kinetics.in)

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Attachment: CaOH_kinetics.in
Description: Binary data

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