Nickel(II) sulfide is insoluble in water and can be formed according to the net ionic equation:

Ni²⁺ (aq) + S^2- (aq) → NiS (s)

Calculate the volume of 0.420 M K₂S (aq) that is required to precipitate all the nickel(II) from 28.0 mL of 0.370 M NiCl₂.

Question

Nickel(II) sulfide is insoluble in water and can be formed according to the net ionic equation:

Ni²⁺ (aq) + S^2- (aq) → NiS (s)

Calculate the volume of 0.420 M K₂S (aq) that is required to precipitate all the nickel(II) from 28.0 mL of 0.370 M NiCl₂.

| General Chemistry 2

Accepted Answer

From the net ionic equation: 1 mole of S^2- is required to precipitate 1 mole of Ni²⁺

⇒ n_S2- = n_Ni2+

n_S2-= n_K2S and n_Ni2+ = n_NiCl2

⇒ n_K2S = n_NiCl2

⇒ M_K2S x V_K2S = M_NiCl2 x V_NiCl2

⇒ V_K2S = $\frac{M_{N i C l 2} \times V_{NiCl 2}}{M_{K 2 S}}$

⇒ V_K2S =

\frac{0.370 \times 28.0}{0.420}

= 24.7 mL

Precipitation reactions | Chemical Reactions and Properties of Solutions