Keywords: reactions of solid oxides with water, acid, base,
Summary: Three solids oxides are added to water. The resulting reactions with water and pH changes are observed by testing with universal indicator and compared to an array of known pH.
Phosphorus pentoxide is corrosive and reacts violently with water.
Chemicals and Solutions:
Calcium oxide or magnesium oxide
three 250 ml beakers (or alternatively three crystallizing dishes)
water (tap water)
three stirring rods
Hint: Because the building DI water source is acidic, tap water must be used in this demo.
Calcium oxide reacts with water to give basic calcium hydroxide:
CaO(s) + H2O(l) è Ca(OH)2(aq)
Phosphorus pentoxide, on the other hand reacts with water to form phosphoric acid:
P4O10 (s) + 6H2O (l) è 4H3PO4 (aq)
Aluminum oxide is amphoteric, it can behave has either and acid or a base. It does not react with water.