mhchem formatting interrupted

Question

\documentclass[12pt,a4paper]{article}
\usepackage[version=3]{mhchem}

\begin{document}
\ce{K_a \times K_b = K_w}
\end{document}

In \ce{} all text is supposed to be regularized. See how the K_a is regularized but then the K_b is italicised and the ensuing K_w is again subject to \ce's regularization. Why does this interruption in formatting happen? I mean, it probably has to do with the \times, but then why does italicised formatting resume after that?

Answer 1

Not sure why it happened, but you can fix it by placing the \times around in a $..$.

\documentclass[12pt,a4paper]{article}
\usepackage[version=3]{mhchem}

\begin{document}
\ce{K_a \times K_b = K_w}

\ce{K_a ${}\times{}$ K_b = K_w}
\end{document}

To keep the proper math spacing I added {} to make the times a binary operator. Alternatively you could use \ce{K_a \mathbin{\times} K_b = K_w}, but I prefer the {}.

Answer 2

You could simply enclose \times in braces:

\documentclass[12pt,a4paper]{article}
\usepackage[version=3]{mhchem}
\begin{document}
\ce{K_a {\times} K_b = K_w}
\end{document}