# Align equilibrium arrows with mhchem

I have the following code made with the mhchem package:

\begin{align}
\ce{CH3COOH + NaOH <=> CH3COONa + H2O} \\
\ce{H2O <=> H^{+}_{(aq)} + OH^{-}_{(aq)}}
\end{align}


Which produces the following output:

Now I'd like to align the two equilibrium arrows. I've only come up with this:

\begin{align}
\ce{CH3COOH + OH-} &\rightleftharpoons \ce{CH3COO- + H2O} \\
\ce{H2O} &\rightleftharpoons \ce{H^{+}_{(aq)} + OH^{-}_{(aq)}}
\end{align}


Which gives this:

The arrows are too short. I've searched and couldn't find any that are longer. I'd like to either a) use the same arrows as mhchem in the second example or b) align the arrows in the first example.

There is a separate command for using \ce in equation environments that allows using ampersands (&) for alignment: \cee

So, no need to work around an make things less readable:

\documentclass{article}
\usepackage[version=3]{mhchem}
\begin{document}
\begin{align}
\cee{CH3COOH + NaOH &<=> CH3COONa + H2O} \\
\cee{H2O &<=> H^{+}_{(aq)} + OH^{-}_{(aq)}}
\end{align}
\end{document}

• That's even better – Argo Nov 9 '14 at 14:25
• In the meantime, also the \ce macro supports & and \\ . There is no need for \cee any more. – mhchem Jun 13 '16 at 18:58
\documentclass{article}
\usepackage[version=3]{mhchem}
\begin{document}
\begin{align}
\ce{CH3COOH + NaOH} & \ce{<=> CH3COONa + H2O} \\
\ce{H2O}& \ce{<=> H^{+}_{(aq)} + OH^{-}_{(aq)}}
\end{align}
\end{document}

• I can't believe I didn't think of that, thanks. – Argo Sep 18 '14 at 14:24