[Baltic Beazt]

hi.
I was given a task to come up with chemical reaction in which from
CuCl2 I was suposed to get H[CuCl2]
now in answers this reaction is shown

CuCl2 + Cu + HCl  2H[CuCl2]

Can anyone explain why is this happening and what exactly H[CuCl2] is.

[DevaDevil]

copper (I) chloride complex: CuCl₂^- is a complex of CuCl and HCl
CuCl does not dissolve much in water, but complexing with the concentrated hydrochloric acid gives this complex and dissolution.

What happens in your reaction is that you have copper (II) chloride, CuCl₂ (s), which can complex with additional halide atoms (e.g. chlorides), to form [CuCl_2+x]^-x.
then the addition of copper metal sets off a redox reaction, in which the copper (0) is oxidized and the copper (II) reduced to form the cooper (I) complex (in hydrochloric acid)

half-reactions:

CuCl₂ + HCl + e^- --> H[CuCl2] + Cl^-
Cu (s) + HCl + Cl^- --> H[CuCl₂] + e^-