Question

Please write a balanced net ionic equation for the confirmation test for copper (in reference to the lab manual Chemical Principles in the Laboratory 11th Edition Experiment 37 ASA question #2C)

Answer 1

Coppper cation may be confirmes by the addition of Ammonia solution to the salt solution of Cu2+ to get a blue color precipitate due ot the formation of Cupric hydroxide(Cu(OH)2)

Cu²⁺(aq) + 2NH₃(aq) + 3H₂O(l) <==> Cu(OH)₂(s) + 2NH₄⁺(aq)

This blue color precipitate soluble in excess of Ammonia due to

Cu(OH)₂(s) + 4NH₃(aq) <==> [Cu(NH₃)₄]²⁺(aq) + 2OH^-(aq)

Cu2+ ions also confirmed by using K4[Fe(CN)6] solution which gives a choclate color precipitate due to formation of Cu2[Fe(CN)6]

2Cu²⁺(aq) + [Fe(CN)₆]^4-(aq) <==> Cu₂[Fe(CN)₆](s)