CB-IN-100/EV: In this experiment, a classic preparation method is proposed for sulphur dioxide from sodium sulphite and hydrochloric acid. You will immediately notice the formation of sulphur dioxide gas (SO2 ) which, bubbling in water, produces an acid solution. Sulphur dioxide in fact reacts with water synthesizing the sulphuric acid. Sulphur dioxide is of great importance in air pollution as it is one of the substances responsible for acid rain. Sulphur dioxide is emitted by power plants, heating systems, industries, and by internal combustion engines. As an alternative to sodium sulphite you can use sodium bisulphite or sodium hydrogen sulphite. CB-IN-101/EV: In this experiment, a classic preparation method is proposed for sulphuric anhydride for a reaction between phosphoric anhydride and sulphuric acid under conditions of cautious heating. The sulphuric anhydride produced is a whitish gas which, on contact with ice, solidifies into whitish needle-like crystals. Sulphuric anhydride also has a strong dehydrating power for which, in order to prevent it absorbing atmospheric moisture, the container must be tightly closed. With water it reacts with a very strong exothermic reaction giving sulphuric acid.
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