chemeq(1)																 chemeq(1)

NAME

       Chemeq - Chemical Equation Analyzer

SYNOPSIS

       chemeq [options]

DESCRIPTION

       Chemeq  is  a chemical equation analyzer. It is a fast lexical and syntaxic analyser which helps to find out chemical informations embedded
       in source chemical equations. Data can be output in various sophisticated formats, depending  on  options.  'chemeq'  defaults  to  'chemeq
       -mlcwCn'.

OPTIONS

       Options	are active only if chemeq parses an equation of chemical reaction. If chemeq parses the formula of a simple chemical, no option is
       taken in account, the output is just a straightforward TeX string representing the simple chemical.

       -h     Displays Help.

       -v     Displays the Version number

       -M     Outputs al list of space separated molecular weights.

       -m     Outputs a Minimal output. It allows chemeq to be idempotent, i.e. the command 'chemeq | chemeq' is equivalent to 'chemeq'.

       -l     Outputs a LaTeX string representing the chemical equation.

       -c     Outputs a message giving informations about the Conservation of elements and charges in the equation. 'OK' means that both  elements
	      and electric charges are balanced.

       -w     Outputs  the  LaTeX string representing the Gulder-Waage equation related to the input chemical equation, or the Nernst equation, if
	      the input equation is a redox semi-equation.

       -C     Outputs a detailed  Count of the molecules and atoms contained in each member of the chemical equation. For example for the equation
	      "H2_g + 1/2 O2_g --> H2O" it outputs: "H2_g|H:1*2, 1/2 O2_g|O:1/2*2; H2O|H:1*2 O:1*1"

       -e     Outputs a detailed count of the Electrical charges.

       -s     Outputs a list of the chemical Species.

       -n     Outputs  a Normalized string accounting for the input equation.  Two chemical equations having the same normalized string are chemi-
	      cally equivalent, even if the molecules are scrambled around and the coefficient are not equal but proportionnal.

ENVIRONMENT VARIABLES

       chemeq_input
	      if set, this variables's value overrides the standard  input. If this variable is not set, the variable w_chemeq_input is  taken	in
	      account (useful for the WIMS server).

       chemeq_option
	      if  set,	this  variable's value overrides the options.If this variable is not set, the variable w_chemeq_option is taken in account
	      (useful for the WIMS server).

EXAMPLES

       echo "1/2 Cu^2+ + OH- ->  1/2Cu(OH)2s" | chemeq
	      will display informations about the reaction of hydroxyde and Cu II ions.

       echo "MnO4^- + 8H3O^+ + 5e- --> Mn^2+ + 12 H2O" | chemeq
	      will display informations about the reaction of reduction of permanganate ions in an acid environment.

       echo "MnO4^- + 8H3O^+ + 5e- --> Mn^2+ + 12 H2O" | chemeq -w
	      will display the LaTeX format for the Nernst law related to the reduction of permanganate ions in an acid environment.

       echo "MnO4^- + 8H3O^+ + 5e- --> Mn^2+ + 8 H2O" | chemeq -c
	      will highlight the lack of conservation of elements H and O (water molecules are not well balanced).

NOTE
: syntax of ions
       allthough in some cases, shorter expressions are sucessfully parsed, it is safer to consider that an "up arrow" (^) must be put before  the
       charge symbols of an ion.  Examples : H3O^+, Fe(CN)6^4-, OH^-

Composing chemical equations.
       Two  operators are defined, # as an additive oprator and ~ (tilde) as a substractive operator: they allow to compose several chemical equa-
       tions

       echo "MnO4^- + 8H3O^+ + 5e- --> Mn^2+ + 8 H2O ~ 5Fe^3+ + 5e- -> 5Fe^2+" | chemeq
	      will display the pure redox equation from the first equation, minus the second one. Electrons are simplified. So it will be  equiva-
	      lent to:

       echo "MnO4^- + 8H3O^+ + 5Fe^2+--> Mn^2+ + 8 H2O + 5Fe^3+" | chemeq
	      which is their combination.

Mutiplying a chemical equation by one coefficient.
       The operator * permits to multiply a whole equation by one coefficient which may be a fraction. Here is an example:

       echo "5 * Fe^3+ + e- -> Fe^2+" | chemeq
	      will be equivalent to

       echo "5Fe^3+ + 5e- -> 5Fe^2+" | chemeq

Combining chemical equations, with coefficients.
       The two previous techniques can be used at the same time, which enables you to make more comlicated combinations, like this one:

       echo "Fe^3+ + e^- -> Fe^2+ (0.77 V) # Fe^2+ + 6CN^- -> Fe(CN)6^4- (Kfa=1e24) ~ Fe^3+ + 6CN^- -> Fe(CN)6^3- (Kfb=1e31)" | chemeq
	      which  will  work  as  expected, and yeld a good value for the standard potential of the redox couple of hexacyanoferrate II and III
	      ions.

AUTHORS

       Georges Khaznadar,
	 <georgesk@ofset.org>

KNOWN BUGS

       When not specified, chemical entities coming from the standard input are believed to be	in  aqueous  solutions.  Water	is  considered	by
       default	as the main solvent. Only one liquid (aqueous) phase is currently taken in account.  All solid chemical entities are considered as
       parts of separated phases.  Suffixes _s, _g and _aq can be used to enforce the type of some chemical entities.

       There may be problemes when you write a standard potential with no decimal dot. For example, the entry Mn^2+ + 2e^- -> Mn_s  (-1  V)  would
       trigger	an  error. Then write Mn^2+ + 2e^- -> Mn_s (-1.0 V) or the more accurate value Mn^2+ + 2e^- -> Mn_s (-1.18 V) and there will be no
       error.

								    4 june 2000 							 chemeq(1)