# mhchem - bold part of equation typeset with \ce{}

I'm trying to typeset a chemical equation using the mhchem package, and I want to bold just one part of the equation (to emphasize the product, in this case).

If I type \ce{a A + b B -> c \textbf{C} + d D}, then that produces a A + b B → c C + d D. That's perfectly fine, of course. But I cannot put any more complex chemical formulas within the \textbf{} command. If I enter, for example, \ce{NH3(g) + HCl(g) -> \textbf{NH4Cl}(s)}, ammonium chloride is typeset as NH4Cl(s), without the subscript.

I tried writing the subscript manually (NH_4Cl), but $\ce{NH3(g) + HCl(g) -> \textbf{NH_4Cl}(s)}$ did not work, and instead gave me a bunch of errors (missing $, extra } or forgotten$, missing {, and missing }).

I'm pretty new here so I'm not exactly sure how this MWE thing works — I don't have much that works, but as far as I can tell the code I was using to try things out seems to be pretty close to a MWE. Please let me know if I should provide anything else.

\documentclass{article}

\usepackage[version=4]{mhchem}

\begin{document}

\ce{a A + b B -> c C + d D}

\ce{a A + b B -> c \textbf{C} + d D}

\ce{NH3(g) + HCl(g) -> \textbf{NH4Cl}(s)}

\end{document}


An \textbf is a hard break inside a \ce. What goes inside \textbf's argument is not processed by the mhchem package.

This is the way to go.

\ce{NH3(g) + HCl(g) -> $\textbf{\ce{NH4Cl}}$(s)}


Use $ to indicate that you want to escape mhchem parsing (mhchem does the correct guessing that \textbf and the next {} belong together, but using $ is much clearer). Then use \textbf, then use \ce inside.

The $ part (or the \textbf for that matter) might interrupt the mhchem flow. The succeeding (s) works fine, here, but you might not be always so lucky (for instance, a $\textbf{4}$ would not be recognized as a number). • Approved! I should have used the same solution as you. – Sebastiano Jul 14 '19 at 9:23 Try • using \ce in math mode (this dose change the output when you use a text font that looks different from the math font, or in headings, as commented by @mhchem) and • using \mathbf instead of \textbf See this example: \documentclass{article} \usepackage[version=4]{mhchem} \begin{document}$\ce{NH3(g) + HCl(g) -> \mathbf{NH_4Cl}(s)}$\ce{NH3(g) + HCl(g) -> NH_4Cl(s)} \end{document}  • Using \ce in math mode does change the output when you use a text font that looks different from the math font, or in headings. – mhchem Jul 14 '19 at 6:21 • @mhchem thanks. I have updated the answer. – muzimuzhi Z Jul 14 '19 at 18:00 It works flawlessly with chemformula, with the difference that the indeterminate coefficients should be typeset in math. \documentclass{article} \usepackage{chemformula} \begin{document} \ch{$a$A +$b$B ->$c$C +$d$D} \ch{$a$A +$b$B ->$c$\textbf{C} +$d\$ D}

\ch{NH3(g) + HCl(g) -> \textbf{NH4Cl}(s)}

\end{document}