Math & Science ⇒ Typesetting "pH"

[chromatic]

Sorry for asking a mundane question, but it's quite difficult to search for a two letter term.

Should I typeset "pH" in mathmode, or is it ok to use textmode? Technically it's a mathmatical function but I'm not sure...!

Thanks

[localghost]

In which mode ever you have to typeset it, you should the excellent siunitx package. The units of chemical or physical quantities are always typeset upright. The package will take care of the correct formatting.


Best regards and welcome to the board
Thorsten

[chromatic]

Thanks localghost.

Turns out I already had siunitx installed - quite new to all this! But, it doesn't seem to recognise "pH" as a unit and I couldn't find any information about it in the instructions [just to check i tried "\si{\meter}" and that works]. I guess I should just leave it as normal text in a paragraph, the paper I'm reading at the moment has it formatted as normal text so I'm sure it's ok.

[localghost]

You can define arbitrary units. Try something like this.

Code: Select all

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{siunitx}

\DeclareSIUnit{\pH}{pH}

\begin{document}
\SI{7}{\pH}
\end{document}

[cgnieder]

May I cite the IUPAC Green Book:

The operator p [...] shall be printed in Roman type. (p 103)

That being said, chemmacros offers commands for pH as well as for pKa and pKb and other uses of the p operator:

Code: Select all

\documentclass{article}
\usepackage{chemmacros,siunitx}

\begin{document}

The \pH\ of the solution is $\pH = \num{4.3}$

The \pKa of acetic acid is $\pKa = \num{4.7}$

\begin{align*}
 \Ka \times \Kb &= 10^{-14} \\
 \pKa + \pKb    &= 14
\end{align*}

\end{document}

Regards

BTW: the pH is not a unit! The Green Book again (emphasis by me): “The quantity pH is defined […]”

[chromatic]

that looks great cgnieder. Only problem is I keep getting errors when I put \usepackage{chemmacros} in the preamble and I can't figure it out.

Console says:

Code: Select all

Runaway argument?
{\(\underset {\bool_if:NF \l_chemformula_name_width_bool {\width_to_dim:Nn \ETC
.
! File ended while scanning use of \NewDocumentCommand.
<inserted text> 
                \par 
l.43 \bool_new:N
                 \l_chemmacros_version_one_bool
? 

[cgnieder]

Which version do you have? The newest one is v3.4 released about two weeks ago.

Regards