I am trying to write chemical equation with \usepackage{chemmacros} but I have a problem.

I want something like that

$...Al + Fe_2O_3 \longrightarrow ...Fe + Al_2O_3$

The dots are for my students.

When I write

\ch{..Fe{} + ...O2 -> Fe3O4}

it's a mess.

Anybody have a solution?

  • 1
    \ldots or \dots?
    – Sigur
    Nov 30, 2013 at 14:39
  • 2
    \ldots works ! great thx :)
    – michaelb
    Nov 30, 2013 at 14:48

1 Answer 1


When a dot is part of a formula or is a single dot (i.e. separated by spaces from other formula parts) it is interpreted as an adduct:

\ch{Na2SO4. 10 H2O}

enter image description here

The same will happen to consecutive dots \ch{...}.

If it is only together with numbers it is interpreted as the decimal mark:

\ch{1.5 Fe}

enter image description here

Here are three possibilities achieving what you want, one of them being simply \ldots as mentioned in the comments. The first version (which I wouldn't use as it looks not so nice) uses chemformula's escaping between " ". The third version uses the math escaping where chemformula adds the same space after it as after a stoichiometric factor (this could be changed with the math-space option).



  manual solution (looks bad IMHO) &
  \ch{"..." Fe + "..." O2 -> Fe3O4} \\
  \texttt{\string\ldots} &
  \ch{\ldots Fe + \ldots O2 -> Fe3O4} \\
  with spacing of stoichiometric factor &
  \ch{$\ldots{}$ Fe + $\ldots{}$ O2 -> Fe3O4}


enter image description here

  • great thx to you :)
    – michaelb
    Nov 30, 2013 at 16:19
  • @michaelb you're welcome! :) If the answer helped you may consider voting for it or even accepting it...
    – cgnieder
    Nov 30, 2013 at 16:24
  • how to ? (my english is a mess too...)
    – michaelb
    Nov 30, 2013 at 16:26
  • @michaelb First of all: it is of course fully up to you if you want to vote or accept! You vote by clicking on the up arrow on the left side of a question or answer (or - if a post is wrong or really bad - on the down arrow). You accept by clicking the check mark below the arrows.
    – cgnieder
    Nov 30, 2013 at 16:30
  • done (i hope...)
    – michaelb
    Nov 30, 2013 at 16:34

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