Tagging custom environments like equations

I'm trying to tag a set of custom environments in the same way I've tagged a set of equations as in the output below. i.e. I'd like "Reaction 1" to display in the same way as "Equation 1" at the end of the line.

I've managed to label the environments correctly with a counter, and they are correctly referenced in the block text. However, I'm unable to find a way to display the tag at the end of the output line. I'm new to LATEX so any suggestions would be greatly appreciated!

Input is as follows:

\documentclass[12pt,a4paper]{report}
\usepackage{chemfig}
\setatomsep{2em}
\usepackage[fleqn]{amsmath}
\setlength{\mathindent}{0pt}
\renewcommand\theequation{Equation\,\arabic{equation}}
\setcounter{equation}{0}

%%%%%%%%%%PROBLEM INPUT
\newcounter{reaction}
\renewcommand\thereaction{Reaction\,\arabic{reaction}}
\setcounter{reaction}{0}
\newenvironment{reaction}[1][]{\refstepcounter{reaction}}
%%%%%%%%%%%%%%%%%%%%%%

\begin{document}

The general formula for the curative needed is given by

\ref{RequiredCurative}.
$$\label{RequiredCurative} a = b + c$$ \par
A generic curing reaction as described above is shown in \ref{Curing} below.\medskip
\begin{flushleft}\begin{reaction}\label{Curing}\chemfig{A-B -> C-D}\end{reaction}\end{flushleft}

\end{document}

• Does your reaction environment have only one line? It is quite easy then. By the way, your reaction environment definition is missing the {} code statement. – user31729 Feb 9 '17 at 22:22
• Thanks. Yes, only one line for the foreseeable cases – AndyC Feb 9 '17 at 23:31
• \hfill will generally overpower things like flushleft, flushright and center. It expands to fill all the unused space in a line. – John Kormylo Feb 10 '17 at 1:52
• Maybe have a look at the numberedblock package: ctan.org/pkg/numberedblock – Steven B. Segletes Feb 10 '17 at 18:06

As there is only one line 'reaction' required, it is sufficient to put the numbering in the end code of the reaction environment. The end code has been missing in the O.P., however.

The macro \reactionfmt is wrapper for easier change of formatting.

\documentclass[12pt,a4paper]{report}
\usepackage{chemfig}
\setatomsep{2em}
\usepackage[fleqn]{amsmath}
\setlength{\mathindent}{0pt}
\renewcommand\theequation{Equation\,\arabic{equation}}
\setcounter{equation}{0}

%%%%%%%%%%PROBLEM INPUT
\newcounter{reaction}
\renewcommand\thereaction{Reaction\,\arabic{reaction}}
\setcounter{reaction}{0}
\newenvironment{reaction}[1][]{\refstepcounter{reaction}}{\hfill\reactionfmt}

\newcommand{\reactionfmt}{(\thereaction)}
%%%%%%%%%%%%%%%%%%%%%%

\begin{document}

The general formula for the curative needed is given by

\ref{RequiredCurative}.
$$\label{RequiredCurative} a = b + c$$ \par
A generic curing reaction as described above is shown in \ref{Curing} below.\medskip
%\begin{flushleft}
\begin{reaction}\label{Curing}
\chemfig{A-B -> C-D}
\end{reaction}
%\end{flushleft}

\end{document}