IF ammonium chloride is formed by counter-current diffusion of ammonia and hydrogen chloride gases in a long tube, periodic precipitation of the product in the form of rings is observed.

It also shows that ammonia and hydrogen chloride (colourless gases) can react to form ammonium chloride again. This slideshow shows a reversible reaction involving white anhydrous copper(II ...

A cotton swab is dipped into concentrated hydrochloric acid (producing hydrogen chloride gas) while a second on is dipped into concentrated aqueous ammonia (producing ammonia gas). Both cotton swabs ...