3

I am currently writing an experimental protocol with overleaf and want to include a redox reaction and both half equations. They should be numbered as 1.1, 1.2 and 1.3, so I am using {align} within {subequations}. I want the half equations to have arrows and oxidation numbers above them to highlight the oxidation and reduction reactions, but I just cannot get it to work.

To make it more clear, I have only included the arrow on the oxidation half equation at this point. The arrow does show up in the lower left corner of the page and not above the oxidation half equation where it should.

Another problem is that the first square bracket in the complex ion [Mn(C_2O_4)_3]^3- within the reduction half equation causes the whole ion and the equilibrium arrows to disappear, which does not happen in the oxidation half equation as there is a stoichiometric coefficient following after the equilibrium arrows.

Here is my code:

\documentclass[titlepage,a4paper,12pt]{article}

\usepackage[]{geometry}
\geometry{a4paper,inner=28mm,outer=18mm,top=20mm,bottom=20mm,footskip=10mm,headsep=5mm,headheight=15mm}

\usepackage{amsmath}

\usepackage{chemmacros}
\usechemmodule{all}
\chemsetup[redox]{explicit-sign = true}
\chemsetup[redox]{pos=top}

\begin{document}

\section{Theorie}

\begin{subequations}
\renewcommand{\theequation}{\theparentequation.\arabic{equation}}
\begin{align}
        %
        % Full reaction
        \ch{KMnO4 + 4 MnSO4 + 15 H2C2O4 &<=> 5 [Mn(C2O4)3]^3- + 22 H^+ + 4 H2O + SO4^2- + K^+}\\
        %
        % oxidation half equation
        \ch{4 "\OX{MnOx1,\ox*{+2,Mn}}" SO4 + 12 H2C2O4 &<=> 4 [ "\OX{MnOx2,\ox*{+3,Mn}}" (C2O4)3]^3- + 24 H^+ + 4 SO4^2- + 4 \el}
        \redox(MnOx1,MnOx2)[->,red]{Oxidation}\\
        %
        % reduction half equation
        \ch{K "\ox{+7,Mn}" O4 + 3 H2CO4 + 4 $\el$ + 2 H^+ &<=> [ "\ox{+3,Mn}" (C2O4)3]^3- + K^+ + 4 H2O}
\end{align}
\end{subequations}

\end{document}

enter image description here

4
  • 2
    Welcome to TEX.SE! Please provide a full minimal working example starting with \documentclass{...} and ending with \end{document} instead of a code snippet. This makes our lives easier and increases the chance of people helping you.
    – campa
    Feb 24, 2021 at 17:17
  • Thank you, I edited the code so it is usable as a working example now.
    – jona173
    Feb 24, 2021 at 17:44
  • 4
    <=> \relax [ should resolve your second problem
    – cgnieder
    Feb 24, 2021 at 18:19
  • It does, thank you!
    – jona173
    Feb 24, 2021 at 18:35

1 Answer 1

2

Not exactly what you seem to have had in mind, but probably nevertheless useful/interesting:

enter image description here

\documentclass[titlepage,a4paper,12pt]{article}

\usepackage[]{geometry}
\geometry{a4paper,inner=28mm,outer=18mm,top=20mm,bottom=20mm,footskip=10mm,headsep=5mm,headheight=15mm}

\usepackage{amsmath}

\usepackage{chemmacros}
\usechemmodule{all}
\chemsetup[redox]{explicit-sign = true}
\chemsetup[redox]{pos=top}


% Definition of subreactions environment from: https://tex.stackexchange.com/a/356406/134144
\makeatletter
\@ifundefined{ignorespacesafterend}{\def\ignorespacesafterend{\global\@ignoretrue}}{}
\newenvironment{subreactions}{%
  \refstepcounter{reaction}%
  \protected@edef\theparentequation{\thereaction}%
  \setcounter{parentequation}{\value{reaction}}%
  \setcounter{reaction}{0}%
  \def\thereaction{\theparentequation\alph{reaction}}%
  \ignorespaces
}{%
  \setcounter{reaction}{\value{parentequation}}%
  \ignorespacesafterend
}
\makeatother


\begin{document}

\section{Theorie}

{\small
\vspace{7mm}
\ch{K "\OX{MnOx7,\ox*{+7,Mn}}" O4 + 4 "\OX{MnOx2,\ox*{+2,Mn}}" SO4 + 15 H2C2O4 <=> 5 [ "\OX{MnOx3,\ox*{+3,Mn}}" (C2O4)3]^3- + 22 H^+ + 4 H2O + SO4^2- + K^+}
\redox(MnOx2,MnOx3)[->,red]{Oxidation}
\redox(MnOx7,MnOx3)[->,blue][-1]{Reduktion}
\vspace{7mm}
\begin{subreactions}
  \begin{reactions}
  &\color{red}Ox:&  4 "\ox*{+2,Mn}" SO4 + 12 H2C2O4 &<=> 4 [ "\ox*{+3,Mn}" (C2O4)3]^3- + 24 H^+ + 4 SO4^2- + 4 \el\\
  &\color{blue}Red:&   K "\ox{+7,Mn}" O4 + 3 H2CO4 + 4 \el + 2 H^+ &<=> \relax [ "\ox{+3,Mn}" (C2O4)3]^3- + K^+ + 4 H2O
  \end{reactions}
\end{subreactions}
}

\end{document}
1
  • This is indeed useful! I would prefer it to be within math mode since I would like to have consistent numbering, but still, this is a great option to go back to!
    – jona173
    Jul 7, 2021 at 19:29

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .