Question

Write the chemical equation for the reaction invovled in extraction of gold from sodium cyanaide

Answer 1

Answer:

$4 Au + 8 CN^{- } + O_2 + 2 H_2O = 4 Au(CN)^{2-} + 4 OH^{2-}$

Explanation:

Firstly, the ore of gold metal is finely ground. It can be concentrated by the metallurgical process of flotation, if the ore of gold metal contains certain impurities, it can be roasted easily. Then, it is mixed with a dilute solution of sodium cyanide while air is bubbled through it. The gold is fully oxidized and forms the soluble Aurocyanide ions. The solution is separated from the ore by the help of the methods such as filtration process, and the gold is precipitated by adding or mixing zinc powder. The precipitate usually contains silver. The silver metal is also precipitated. The silver metal is unreacted with zinc.

The process of extracting gold from ore with cyanide is called cyanidation. The reaction which is written below is known as Elsner's Equation. Please look:

$4 Au + 8 CN^{- } + O_2 + 2 H_2O = 4 Au(CN)^{2-} + 4 OH^{2-}$