It's very convenient to use mhchem to typeset chemical formulas. It works very good in English writing, but when using Chinese (ctex), every chemical formula is followed by a space, which makes the text ugly. How to solve this small (but seemingly not so trivial) problem? Thanks.
Here is what I mean.
\usepackage[version=4]{mhchem}
There is no space after \ce{HNO3} in English environment.
如果是在中文的环境中\ce{HNO3}会有一个空格。
Which gives the result:
The space appears to be added by the ctex code when switching from Latin script to Chinese. The above is generated with xelatex. Note the space is also added after !! placing an empty \mbox{} seems to suppress it, as shown in the last line.
\documentclass{article}
\usepackage[UTF8]{ctex}
\usepackage[version=4]{mhchem}
\begin{document}
\showoutput
(\ce{HNO3})
AA \ce{HNO3} BB
中\ce{HNO3}会
中\ce{HNO3}!!会
中\ce{HNO3}\mbox{}会
\end{document}
with xetex the space seems to be added in the \XeTeXinterchartoks code, and for luatex the output is different, with no space after !! but still space after the Chemical formula.
texdoc ctex but it's not the easiest read.
Commented
Mar 24, 2020 at 19:24
\ch{HNO3}in combination with\usepackage{chemformula}is an alternative?\unskipafter\ce{HNO3}to remove the space, but please supply complete small document not just a fragment so answers can be tested(\ce{HNO3})in English? There should be no space between3and).xeCJK, which tries to automatically add a space between CJK characters and non-CJK ones. This works well for plain input, for exampleabc<auto space>中文<auto space>abc. However, in the case ofabc \cmd{...} abc，xeCJKmay make mistakes. When compiled with xetex,ctexauto loadsxeCJK.\ceis not the only one which may cause problems withxeCJK. So don't worry. I have opened an issue on the repository ofxeCJK, to ask for a general solution.