The formation of red metal on ignition in presence of carbon
name: Reduction of copper from salts in the presence of carbon
The first step of the synthesis proceeds with the formation of copper carbonate through an ordinary ion exchange reaction. The need for use of sodium bicarbonate (baking soda) is due to the fact that the reaction between copper sulfate and sodium carbonate leads to the formation of basic copper carbonate, which is less suitable for the next step.
Copper carbonate is easily decomposed by heating to copper oxide and carbon dioxide. However, copper oxide reduces to copper metal in the presence of a reducing agent (carbon).