Question

NiCl2 + 2NaOH = 2NaCl + Ni(OH)2↓ Ni+2 + 2Cl- + 2Na+ + 2Cl- = 2Na+ + 2Cl- + Ni(OH)2↓ Ni+2 + 2OH- = Ni(OH)2↓ – выпадает осадок зеленого цвета Ni(OH)2 + 2HCl = NiCl2 + 2H2O Ni(OH)2 + 2H+ +2Cl- = Ni2+ + 2Cl- + 2H2O Ni(OH)2 + 2H+ = Ni2+ 2H2O – осадок растворяется. Почему в ходе реакции осадок растворился? с чем это связано? как можно объяснить?

Answer 1

Ответ:

в 1 варианте получился гидроксид нитыя( название точно не помню)

во 2 варианте просто нитый(название точно не помню) и вода по этому получается что вещество растворилось

Answer 2

Explanation of the Reaction and Dissolution of the Precipitate

The reaction you've described involves the reaction of nickel(II) chloride (NiCl2) with sodium hydroxide (NaOH) to form nickel(II) hydroxide (Ni(OH)2) as a precipitate, which then dissolves under certain conditions. Let's break down the reaction and the dissolution of the precipitate.

Formation of Precipitate: The reaction between nickel(II) chloride and sodium hydroxide can be represented as follows: NiCl2 + 2NaOH → 2NaCl + Ni(OH)2↓

This reaction results in the formation of a green precipitate of nickel(II) hydroxide.

Dissolution of the Precipitate: The dissolution of the precipitate can be explained by the reaction with excess hydroxide ions or acidic conditions.

1. Excess Hydroxide Ions: When excess hydroxide ions are added, the precipitate can redissolve due to the formation of a complex ion. The reaction can be represented as: Ni(OH)2 + 2OH- → Ni(OH)4^2-

The formation of the complex ion Ni(OH)4^2- leads to the dissolution of the precipitate, resulting in a clear solution.

2. Acidic Conditions: Under acidic conditions, the precipitate can also dissolve. The reaction can be represented as: Ni(OH)2 + 2H+ → Ni^2+ + 2H2O

In acidic conditions, the nickel(II) hydroxide reacts with the hydrogen ions to form nickel(II) ions and water, leading to the dissolution of the precipitate.

Factors Affecting Precipitate Dissolution

The dissolution of the precipitate is primarily related to the formation of complex ions or the reaction with acidic conditions. The solubility of metal hydroxides, including nickel(II) hydroxide, is influenced by the pH of the solution. In alkaline conditions (high pH), the hydroxide ions can form complex ions with the metal hydroxides, leading to their dissolution.

Conclusion

In summary, the dissolution of the green precipitate of nickel(II) hydroxide is attributed to the formation of complex ions in the presence of excess hydroxide ions or the reaction with acidic conditions. These reactions result in the dissolution of the precipitate and the formation of a clear solution.