When an orange-yellow volcano ignites it produces a dark dense liquid.
name: Oxalic acid is oxidized by dichromate ions.
Удивительный опыт - Реакция бихромата аммония
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(NH4)Cr2O7 + 7H2C2O4 → 6CO2 + 3H2O + 2NH4(Cr(C2O4)2(H2O)2)
- Prepare 6 g of oxalic acid (H2C2O4*2H2O) and 4 g of ammonium bichromate ((NH4)2Cr2O7.
- Grind the substances separately in a mortar.
- Mix the components together and pour them on a fire-proof plate to form a volcano.
- Ignite it with a burning splint.
- When you touch the mixture with the splint a bubbling dark drop appears.
- In a short time the whole volcano turns into a dark puddle.
This experiment is based on the oxidation reaction between oxalic acid and dichromate ions. As the result water, carbon dioxide and ammonium dioxalato diaquo chromium (III) complex are produced. The reaction is accompanied with the evolution of heat. The initial orange-yellow mixture turns to a viscous bubbling liquid. The bubbles are formed by liberating carbon dioxide. Dark green (almost black) color of “mud” is caused by the formation of trivalent chromium.