[Tex/LaTex] Equation number on wrong line

equationsnumbering

Hi my equations produce their numbers on the following line as opposed to the same line.
Here's an example

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\begin{equation}$$ $I_{3}^{-}(sol) \longleftrightarrow I_{2}(sol)+I^{-}(sol)...  Dissociation$ $$ \end{equation}
\end{document}

Best Answer

(By request, here's my comment posted as an answer. You should be on the lookout for a specialised chemistry package to typeset such equations in a clear and consistent way — the advice in this answer is generic to displayed math in general.)

You only need to use a displayed math environment such as equation or gather, if you want to display a single equation. Also, you should put explanatory text (such as Dissociation inside the argument of a \text command; and labels which are part of the equation (such as (sol) for your ions) should be put inside the argument of a command such as \mathrm.

Example.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
     I_{3}^{-}\textrm{(sol)}
  \longleftrightarrow
     I_{2}\textrm{(sol)}+I^{-}\textrm{(sol)}
  \qquad
     \text{\ldots Dissociation}
\end{equation}
\end{document}

Sample chemical formula

Related Question