What are the following reactions? Redox, acid base, or precipitate? A:Cu (s) + 2 NO3− (aq) + 4 H+ (aq) + 4 H2O (l) →  [Cu(H2O)6]2+ (aq) + 2 NO2 (g) B:  [Cu(H2O)6]2+ (aq) + 2 OH- (aq) → Cu(OH)2 (s) + 6 H2O (l) C:  Cu(OH)2 (s) → CuO (s) + H2O (l) D:  CuO (s) + 2 H+ (aq) + 5 H2O (l) → [Cu(H2O)6]2+ (aq) E:  [Cu(H2O)6]2+ (aq) + Zn (s) → Cu (s) + Zn2+ (aq) + 6 H2O (l)  

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Redox or reduction-oxidation reactions refer to those where there is a transfer of electrons from one substance to the another. The substance losing electrons is being oxidized and the one gaining electrons is being reduced. In an acid base reaction water is one of the end products. A precipitation reaction leads to the formation of a product that is insoluble.

The chemical reactions that have to be classified are:

 

`Cu(s) + 2(NO_3)^(-) (aq) + 4 H^+(aq) + 4 H_2O`

`-> [Cu(H_2O)_6]^(2+) (aq) + 2 NO_2 `

This is a redox reaction. Copper is being oxidized, the positive ion then binds with 6 molecules of water. NO_3^- is converted to NO_2 gas.

`[Cu(H_2O)_6]^(2+) + 2 OH^(-) (aq) -> Cu(OH)_2 (s) + 6 H_2O (l)`

In this reaction, copper hydroxide is precipitated. This is a precipitation reaction.

`Cu(OH)_2 (s) -> CuO (s) + H_2O (l)`

This is a precipitation reaction.

`CuO (s) + 2 H^+ (aq) + 5 H_2O (l) -> [Cu(H2O)6]^(2+) (aq)`

This is a redox reaction.

`[Cu(H_2O)_6]^(2+) (aq) + Zn (s) -> Cu (s) + Zn^(2+) (aq) + 6 H_2O (l)`

This is also a redox reaction.

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