# How can I write these chemical reaction equations?

Trying to write a thesis, and I need some reaction equations. How can I write this in LaTeX?

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\rightleftarrows, \underset{…}{…} and \overset{…}{…} might be your friends. –  Manuel Mar 16 at 23:32
Will do. New at LaTex. Thanks –  Demetri P Mar 16 at 23:32
Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. –  Paul Gessler Mar 17 at 0:03

There are a couple of packages for typesetting chemistry stuff, one such is chemmacros. The equation in your image can be typeset as

\ch{S + E <>[ $k_{\mathrm{SI}}$ ][ $k_{\mathrm{IS}}$ ] E.I <>[ $k_{\mathrm{PI}}$ ][ $k_{\mathrm{IP}}$ ] P + E}


which will give

I suggest you take a look at the manual for the package. It is probably installed along with the package in your TeX distribution, and you can find it by writing texdoc chemmacros in a command prompt/terminal (or in the search field in the start menu, if you're on Windows). Or you can get it at http://www.ctan.org/pkg/chemmacros

Complete code:

\documentclass{article}
\usepackage{chemmacros}

\begin{document}
\ch{S + E <>[ $k_{\mathrm{SI}}$ ][ $k_{\mathrm{IS}}$ ] E.I <>[ $k_{\mathrm{PI}}$ ][ $k_{\mathrm{IP}}$ ] P + E}
\end{document}

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I actually found a simpler method, but this is very useful. I will keep this in mind. –  Demetri P Mar 16 at 23:57
Ups, this is a great answer, I missed the {chemistry} label in my comment. –  Manuel Mar 16 at 23:59
@DemetriP Please write up your simpler way as an answer. It's fine to answer your own questions: one of the goals of the site is to build up a repository of good answers to questions so that other people can use the answers too. –  David Richerby Mar 17 at 2:00

I used the following code to write the equation

S+E  \xrightleftharpoons[k_{IS}]{k_{SI}}  I \cdot E \xrightleftharpoons[k_{PI}]{k_{IP}} P+E


the \xrightleftharpoons allows you to specify what goes on top/bellow of the arrows.

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Welcome to TeX.SX! Please make your code compilable (if possible), or at least complete it with \documentclass{...}, the required \usepackage's, \begin{document}, and \end{document}. That may seem tedious to you, but think of the extra work it represents for TeX.SX users willing to give you a hand. –  Henri Menke Mar 17 at 9:40