1\documentclass{article} 2\usepackage{amssymb} 3\begin{document} 4 5\section{Chemistry} 6 7Ex: 8Soaps are essentially useless in acidic water, because in acidic water the carboxylate 9ions of soap molecules pick up hydogen ions to form the undissociated fatty acid: 10 11$$RCCO^- \quad + \quad H^+ \quad\longleftarrow\quad RCOOH$$ 12 13$$RCCO^- \quad + \quad H^+ \quad\longrightarrow\quad RCOOH$$ 14 15$$RCCO^- \quad + \quad H^+ \quad\longleftrightarrow\quad RCOOH$$ 16 17$$RCCO^- \quad + \quad H^+ \quad\Longleftarrow\quad RCOOH$$ 18 19$$RCCO^- \quad + \quad H^+ \quad\Longrightarrow\quad RCOOH$$ 20 21$$RCCO^- \quad + \quad H^+ \quad\Longleftrightarrow\quad RCOOH$$ 22 23$$RCCO^- \quad + \quad H^+ \quad\rightleftarrows\quad RCOOH$$ 24 25$$RCCO^- \quad + \quad H^+ \quad\leftleftarrows\quad RCOOH$$ 26 27$$RCCO^- \quad + \quad H^+ \quad\rightrightarrows\quad RCOOH$$ 28 29$$RCCO^- \quad + \quad H^+ \quad\leftrightarrows\quad RCOOH$$ 30 31\end{document} 32