Question

Why does clean copper, after being dipped in acetic acid + common salt, acquire a greenish-blue layer after it is dried with a tissue? Write the compound formed, it's chemical formula and the chemical and word equation.

Answer 1

Acetic acid and salt when reacts with copper it liberates copper oxide which when dried forms bluish-green substance called malachite. Malachite (Cu2CO3(OH)2) is a copper carbonate hydroxide mineral. CuO + 2CH3COOH --> Cu(CH3COO)2 ( copper acetate) + H2O Copper acetate when dried gives malachite.