chemeq - Chemical Equation Parser and Renderer
[ -M] [-m] [-l] [-c] [-w] [-C]
[-e] [ -s] [-n] [-W]
[ -h] [-v]
is a chemical equation analyzer. It is a fast lexical and syntaxic
analyser which helps to find out chemical information embedded in source
chemical equations. Data can be output in various sophisticated formats,
depending on options. 'chemeq' defaults to 'chemeq -mlcwCn'.
Outputs al list of space separated molecular
Outputs a minimal output. It allows
chemeq to be idempotent, i.e. the command 'chemeq | chemeq' is equivalent to
Outputs a LaTeX string representing the
Outputs a message giving information about the
Conservation of elements and charges in the equation. 'OK' means that both
elements and electric charges are balanced.
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.
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"
Outputs a detailed count of the
Outputs a list of the chemical
Outputs a Normalized string accounting
for the input equation. Two chemical equations having the same normalized
string are chemically equivalent, even if the molecules are scrambled around
and the coefficient are not equal but proportionnal.
Changes the behavior of the renderer for some
versions of Wims : works around a bug with the macro \rightarrow.
Displays the Version number
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). See above (useful for the WIMS
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).
See above (useful for the WIMS server).
echo "1/2 Cu^2+ + OH- -> 1/2Cu(OH)2s" | chemeq
will display information about the reaction of
hydroxyde and Cu II ions.
echo "MnO4^- + 8H3O^+ + 5e- --> Mn^2+ + 12 H2O" | chemeq
will display information 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
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).
syntax of ions
although in some cases, shorter expressions
are successfully parsed, it is safer to consider that an "up arrow"
(^) must be put before the charge symbols of an ion. Examples : H3O^+,
Composing chemical equations
Mutiplying a chemical equation by one coefficient
Two operators are defined, # as an additive
oprator and ~ (tilde) as a substractive operator: they allow one to compose
several chemical equations
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 equivalent to:
echo "MnO4^- + 8H3O^+ + 5Fe^2+--> Mn^2+ + 8 H2O + 5Fe^3+" |
which is their combination.
Combining chemical equations, with coefficients
The operator * permits one 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
The two previous techniques can be used at the
same time, which enables you to make more comlicated combinations, like this
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 yield a good value for the stan‐ dard
potential of the redox couple of hexacyanoferrate II and III ions.
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)
the more accurate value Mn^2+ + 2e^- -> Mn_s (-1.18 V)
will be no error.
Wrote this manpage.
Copyright © 2000-2013 Georges Khaznadar
Redistribution and use of this manpage in source and binary forms, with or
without modification, are permitted under the terms of the GNU General Public
Licenses, version 2
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