Question

The Cu2+ ion can be separated from Ag+,
Ca2+, and K+ in aqueous solution by
1. precipitation of Cu2+ as Cu(OH)2(s) with
6 M NaOH(aq).
2. precipitation of Ag+, Ca2+, and K+ as
the carbonates.
3. None of these procedures will separate
Cu2+ from the other ions.
4. precipitation of Cu2+ as CuCl2(s) with 6
M HCl(aq).
5. precipitation of Cu2+ as CuS(s) at pH 1.

Answer 1

The Cu2+ ion can be separated from Ag+,
Ca2+, and K+ in aqueous solution by
1. precipitation of Cu2+ as Cu(OH)2(s) with 6 M NaOH(aq).
<b>Cu(OH)2 will ppt but so will Ag(OH)2/Ag2O.</b>

2. precipitation of Ag+, Ca2+, and K+ as
the carbonates.
<b>CuCO3 will ppt with Ag2CO3 and K^+ will not</b>\
3. None of these procedures will separateCu2+ from the other ions.
<b>I think this is the best answer.</b>

4. precipitation of Cu2+ as CuCl2(s) with 6 M HCl(aq).
<b>Absolutely not. CuCl2 is soluble.</b>

5. precipitation of Cu2+ as CuS(s) at pH 1.
<b>The solubility of Ag2S and CuS are more or less the same at pH=1 so that will not separate the two. </b>