Math & Science ⇒ Mass of Substances in Reaction Equation

[drmCA]

What is the best practice to include molar mass of reagents in \ce macro?

[localghost]

What is the expected result?


Thorsten

[cgnieder]

It is not common at all to include molar masses into chemical equations. This means there cannot be a best-practice for it. Just for fun here is a possible way with my chemmacros package or rather its sub-package chemformula:

Code: Select all

\documentclass{article}
\usepackage{chemformula}
\usepackage{siunitx}
\sisetup{per-mode=symbol}
\begin{document}
\ch{!(\SI{18}{\gram\per\mole})( H2O ) + !(\SI{23}{\gram\per\mole})( 4 Na ) -> ??}
\end{document}

chemformula.png (4.1 KiB) Viewed 9562 times

Regards

[drmCA]

This is the desired result. Is the same possible with mhchem?

It is not common at all to include molar masses into chemical equations. This means there cannot be a best-practice for it. Just for fun here is a possible way with my chemmacros package or rather its sub-package chemformula:

Code: Select all

\documentclass{article}
\usepackage{chemformula}
\usepackage{siunitx}
\sisetup{per-mode=symbol}
\begin{document}
\ch{!(\SI{18}{\gram\per\mole})( H2O ) + !(\SI{23}{\gram\per\mole})( 4 Na ) -> ??}
\end{document}

chemformula.png

Regards

[Johannes_B]

The documentation shows an example with \underset. But in comparison, chemformula makes it more easy to handle.

Code: Select all

\documentclass{article}
\usepackage{chemformula}
\usepackage{mhchem}
\usepackage{siunitx}
\sisetup{per-mode=symbol}
\DeclareSIUnit\molmass{\gram\per\mole}
\begin{document}
\ch{!(\SI{18}{\gram\per\mole})( H2O ) + !(\SI{23}{\gram\per\mole})( 4 Na ) -> ??}

\vspace{1em}

\ce{$\underset{\SI{18}{\molmass}}{\ce{H2O}}$ + $\underset{\SI{23}{\molmass}}{\ce{4Na}}$}
\end{document}

Best regards

[cgnieder]

The documentation shows an example with \underset. But in comparison, chemformula makes it more easy to handle.

Code: Select all

\documentclass{article}
\usepackage{chemformula}
\usepackage{mhchem}
\usepackage{siunitx}
\sisetup{per-mode=symbol}
\DeclareSIUnit\molmass{\gram\per\mole}
\begin{document}
\ch{!(\SI{18}{\gram\per\mole})( H2O ) + !(\SI{23}{\gram\per\mole})( 4 Na ) -> ??}

\vspace{1em}

\ce{$\underset{\SI{18}{\molmass}}{\ce{H2O}}$ + $\underset{\SI{23}{\molmass}}{\ce{4Na}}$}
\end{document}

Best regards

While the mhchem solution works v3.11 it doesn't with v3.12:

Code: Select all

! Missing $ inserted.
<inserted text> 
                $
l.12 ... $\underset{\SI{23}{\molmass}}{\ce{4Na}}$}

It works on writeLaTeX with following versions ...

• pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012)
• mhchem.sty 2011/06/03 v3.11
• chemformula.sty 2012/07/24 v3.3d

... while I get the above mentioned error with following versions:

• pdfTeX, Version 3.1415926-2.5-1.40.14 (TeX Live 2013)
• mhchem.sty 2013/06/17 v3.12
• chemformula.sty 2013/07/06 v4.0

Also, I think the \underset solution is visually not ideal:

molmass.png (6.74 KiB) Viewed 9537 times

Regards

[Johannes_B]

While the mhchem solution works v3.11 it doesn't with v3.12:

Code: Select all

! Missing $ inserted.
<inserted text> 
                $
l.12 ... $\underset{\SI{23}{\molmass}}{\ce{4Na}}$}

It works on writeLaTeX with following versions ...

• pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012)
• mhchem.sty 2011/06/03 v3.11
• chemformula.sty 2012/07/24 v3.3d

... while I get the above mentioned error with following versions:

• pdfTeX, Version 3.1415926-2.5-1.40.14 (TeX Live 2013)
• mhchem.sty 2013/06/17 v3.12
• chemformula.sty 2013/07/06 v4.0

Hi Clemens,

you are right. I forgot to check on my system. I didn't even took a close enough look to notice the bad spacing.
Strange tough, that the underset-example still is in the recent version 3.13 (2013/07/02) of the manual. And more strange, that the file list shows

Code: Select all

mhchem.sty    2013/06/17 v3.12 for typesetting chemical formulae

To put it in a nutshell, while mhchem still got the status maintained, using chemmacros is highly recommended.

[cgnieder]

Strange tough, that the underset-example is still in the recent version 3.13 (2013/07/02) of the manual. And more strange, that the file list shows

Code: Select all

mhchem.sty    2013/06/17 v3.12 for typesetting chemical formulae

I think I might have an explanation for both points (without having checked the files in question, though): it's only the second \underset that causes an error, the following compiles fine:

Code: Select all

\documentclass{article}
\usepackage{mhchem}
\usepackage{siunitx}
\sisetup{per-mode=symbol}
\DeclareSIUnit\molmass{\gram\per\mole}
\begin{document}
\ce{$\underset{\SI{18}{\molmass}}{\ce{H2O}}$}% + $\underset{\SI{23}{\molmass}}{\ce{4Na}}$}
\end{document}

So Martin probably hasn't noticed the issue.

As for the version number: Martin probably forgot to update the package info in the line

Code: Select all

\ProvidesPackage{mhchem}[<versioning and info>]

Maybe someone should tell him...

Regards

[Johannes_B]

I guess you have been in contact with him in the past. Could you do that?