The compound KCN is traditionally used to extract gold from ore. Gold dissolves in cyanide solution in the presence of air to form $Au (CN)_{2}^{-}$ .
How many grams of KCN are needed to extract 20 gram of gold from ore?
(Atomic weight of Au = 197 , K = 39 , C = 12 , N = 14)

Question

The compound KCN is traditionally used to extract gold from ore. Gold dissolves in cyanide solution in the presence of air to form $Au (CN)_{2}^{-}$ .

How many grams of KCN are needed to extract 20 gram of gold from ore?

(Atomic weight of Au = 197 , K = 39 , C = 12 , N = 14)

TestHub · Accepted Answer

4 Au + 8 KCN + O 2 ​ + 2 H 2 ​ O ⇌ 4 KAu ( CN ) 2 ​ + 4 KOH 20 g ÷ 197 g mol − 1 ≈ 0.10 mol ( Au ) 0.10 mol × ( 8/4 ) × 65.00 g mol − 1 = 13.00 g KCN

Chemistry - Metallurgy Question with Solution | TestHub

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