Question

PART A: Cu (s) + 2 NO3- (aq) + 4 H+ (aq) + 4 H20 (1) → [Cu(H20)6]2+ (aq) + 2 NO2(g) (1) PART B: [Cu(H20)6]2+ (aq) + 2 H20 - (aq) + Cu(OH)2 (5) + 6 H20 (1) PART C: Cu(OH)2 (s) → CuO (s) + H20 (1) PART D: CuO (s) + 2 H+ (aq) + 5 H20 (1) → [Cu(H20)6]2+ (aq) PART E: [Cu(H20)6]2+ (aq) + Zn (s) → Cu (s) + Zn2+ (aq) + 6 H20 (1)

What type of reaction is occurring in each step? Give a brief description for your choice. Provide a complete balanced reaction equations for the two redox reactions. Indicate which species is being oxidize and which is being reduced in each case.

Answer 1

Ans PART A: It is a redox reaction.

Reduction oxidation number 0 +5 +2 +4 Cu(s) + 2 (NO3)" (aq) + 4 H+ (aq) + 4 H20 (1) — [Cu(H20)]2+ (aq) + 2 NO2 (g) Oxidation Balanced equation: 1 Cu(s) + 2 (NO) (aq) + 4H+ (aq) + 4H2O (1) - 1 [Cu(H20)6] + (aq) + 2 NO2 (g)

It is a redox reaction.

Here 'Cu' is undergoing oxidation. (Increase in oxidation number)

And, 'N' in (NO₃)^- is undergoing reduction. (Decrease in oxidation number)

Ans PART B: It is a precipitation reaction

Cu(H₂O)₆]²⁺ (aq) + 2 (OH)^- ----> Cu(OH)₂ (s) + 6 H₂O (l)

Cu(OH)₂ is getting precipitated out during the reaction due to the addition of (OH)^- to [Cu(H₂O)₆]²⁺.

Ans PART C: dehydration reaction

Cu(OH)₂ (s) ---> CuO (s) + H₂O (l)

It is a dehydration reaction.

Cu(OH)₂ looses a molecule of water to give CuO.

Ans PART D: coordination complex formation reaction

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

CuO solid in aqueous acidic medium forming a coordination complex [Cu(H₂O)₆]²⁺. During this reaction we can see CuO dissolving upon addition of acid.

Ans PART E: REDOX reaction

Oxidation oxidation number +2 [Cu(H20)612+ (aq) + Zn (s) +2 Cu (s) + Zn2+ (aq) + 6H2O (1) Reduction Balanced equation: [Cu(H,0) 12+ (aq) + Zn (s) — Cu(s) + Zn2+ (aq) + 6 H20 (1)

It is a redox reaction.

Here 'Cu' is undergoing reduction. (Decrease in oxidation number)

And, 'Zn' is undergoing oxidation. (Increase in oxidation number)