% John David Stone
% Department of Mathematics and Computer Science
% Grinnell College
% stone@cs.grinnell.edu

% created June 21, 2002
% last revised June 21, 2002

\documentclass[11pt]{article}
\usepackage{amsmath}

\newcommand{\pot}{\textrm{K}}
\newcommand{\man}{\textrm{Mn}}
\newcommand{\oxy}{\textrm{O}}
\newcommand{\hyd}{\textrm{H}}
\newcommand{\bro}{\textrm{Br}}
\newcommand{\ars}{\textrm{As}}
\newcommand{\sul}{\textrm{S}}
\newcommand{\nit}{\textrm{N}}
\newcommand{\iro}{\textrm{Fe}}

\begin{document}
\begin{align*}
2\pot\man\oxy_4 + 8\hyd_2\sul\oxy_4 + 10\pot\bro &\longrightarrow
6\pot_2\sul\oxy_4 + 5\bro_2 + 2\man\sul\oxy_4 + 8\hyd_2\oxy \\
3\ars_2\sul_3 + 4\hyd_2\oxy + 28\hyd\nit\oxy_3 &\longrightarrow
28\nit\oxy + 6\hyd_3\ars\oxy_4 + 9\hyd_2\sul\oxy_4 \\
3\iro_7\sul_8 + 38\oxy_2 &\longrightarrow 7\iro_3\oxy_4 + 24\sul\oxy_2
\end{align*}
\end{document}