Ammonia and hydrochloric acid: Chemistry in Pictures winner
March 2014, Chem 13 News Magazine
By Carlos Corrêa, at the Faculdade de Ciências, Universidade do Porto, Portugal
Carlos Corrêa, at the Faculdade de Ciências, Universidade do Porto, Portugal, sent in this photo capturing the acid-base reaction between ammonia and hydrochloric acid. Inside the bottle it is the vapours of the acid and the base that react. The product is ammonium chloride, which is a solid and appears as white smoke. Have your students write out the chemical reaction — don’t forget to include the states of matter — and have them find the heat of reaction. Another challenge would be to have your students explain the pathway of the smoke — the fine particles of NH4Cl — as it appears to float out of the bottle, and then begins to track downwards. A lot of chemistry is captured in this simple photo.