Question

Silver is often extracted from ores such as k[ag(cn)2] and then recovered by the reaction 2k ⎡ ⎣ag(cn)2 ⎤ ⎦(aq) + zn(s) ⟶ 2ag(s) + zn(cn)2 (aq) + 2kcn(aq) (a) how many molecules of zn(cn)2 are produced by the reaction of 35.27 g of k[ag(cn)2]? (b) what mass of zn(cn)2 is produced?

Answer 1

Take note of the whole number beside each substance in the reaction because these will be used in the stoichiometric calculations below:

Molar mass of k[ag(cn)2]:199 g/mol
Molar mass of Zn(Cn)2: 117.44 g/mol
Avogadro's number: 6.022×10²³ molecules/mol

a.)

35.27 g*(1 mol/199 g)*(1 mol Zn(Cn)₂/ 2 mol K[Ag(CN)₂])*(6.022×10²³ molecules/mol) = 5.34×10²² molecules of Zn(Cn)₂

b.)

35.27 g*(1 mol/199 g)*(1 mol Zn(Cn)₂/ 2 mol K[Ag(CN)₂])*(117.44 g/mol) = 10.41 g of Zn(Cn)₂