An experience. In a porcelain mortar, 50 g of orange-red ammonium dichromate crystals are carefully ground. Powder (NH4)2Cr2O7 is poured onto a large metal plate or sheet of asbestos paper, the shape of the roller coaster - this will be our "volcano". At the top of the "volcano" a nail or a stick is made a funnel and poured into it 1-2 ml of ethyl alcohol. Alcohol is ignited with a match, and the light in the room is turned off. From the heat of combustion of alcohol, ammonium dichromate begins to rapidly decompose. At the same time a sheaf of bright sparks is emitted from the "crater of the volcano" and "volcanic ash" is a dirty-green Cr2O3, whose volume is many times larger than the volume taken (NH4)2Cr2O7:

At the top of the volcano a nail or a stick is made a funnel and poured into it 1-2 ml of ethyl alcohol

(NH4)2r2O7 = N2 + 42O + r2O3 + Q.

Exothermic decay (NH4)2Cr2O7 is very similar to a real volcano.

An experience. In a large and wide test tube, 2-3 g of finely ground potassium permanganate are poured and the test tube is fixed in a tripod with a hole upward. Carefully pour into the tube, or pipette, 1-2 ml of concentrated H2SO4.

From a blotting or filter paper, small balls are made and, at intervals, they are dropped into a test tube. In this case, paper balls burst with a crash, and "volcanic ash" - brown MnO2 or, more precisely, Mn(OH)2 - the product of the reduction of permanganate anhydride by the tissue of paper:

2n4 + 22SO4 = 2SO4 + (2n4),

n4 = 2O + n2O7,

4nn2O7 + (610O5)n = 8nn2 + 5n2O + 6nCO2.

The phenomenon of chemical "volcano" is very spectacular. Instead of a paper ball in a tube with KMnO4 and H2SO4, you can drop, for example, a watt tampon.