       simultaneous equations for chemical speciation

• To: mathgroup at smc.vnet.net
• Subject: [mg100186] simultaneous equations for chemical speciation
• From: Jem & Tracy <jemandtracy at bigpond.com>
• Date: Wed, 27 May 2009 04:09:01 -0400 (EDT)

```Hi, I am a postgrad student and completely new to mathematica, I am just
starting to realise the possibilities.

I am trying to do a chemical speciation calculation.
I have a set of simultaneous equations which represents the equilibria,
mass balance, and charge balance in the system.

I want to eliminate some of the variables, and then be able to solve for
the remaining ones.
My system of equations looks like this:
a=b+c+d
e=f+g+c+2d
h=c/(bg)
i=d/(cg)
hi=d/(bg^2)
j=mg/f
k=lm
n+m+b+c=g+l

Basically, I can solve for the variable I want, but I am having trouble
eliminating the ones I don't want (ie. I am getting an answer that is in
terms of the wrong variables)
Sofar my formula looks like:

Solve[{a == b + c + d, e == f + g + c + 2 d, h == c/(b*g),
i == d/(c*g), h*i == d/(b*g^2), j == m*g/f, k == l*m,
n + m + b + c == g + l}, {g}]

If I use a similar formula for the "Eliminate" function, I get error
mesages.

I have been in the help files for ages, and don't really understand how
to do this.
I would really appreciate some pointers!!
Thanks

```