A solution of 100.0 mL of 0.200 M KOH is mixed with a solution of 200.0 mL of 0.150 M NiSO_4. (b) What precipitate forms?

Verified step by step guidance

1. Identify the ions present in each solution: KOH dissociates into K^+ and OH^- ions, while NiSO_4 dissociates into Ni^{2+} and SO_4^{2-} ions.
2. Determine the possible combinations of ions that could form a precipitate: K^+ with SO_4^{2-} and Ni^{2+} with OH^-.
3. Use the solubility rules to determine which combination forms a precipitate: K_2SO_4 is soluble, while Ni(OH)_2 is insoluble.
4. Conclude that Ni(OH)_2 is the precipitate that forms when the solutions are mixed.
5. Write the balanced chemical equation for the precipitation reaction: Ni^{2+} (aq) + 2OH^- (aq) \rightarrow Ni(OH)_2 (s).

Key Concepts

Precipitation Reactions

Precipitation reactions occur when two soluble salts react in solution to form an insoluble compound, known as a precipitate. This process is driven by the formation of a product that is not soluble in the solvent, leading to the separation of the solid from the liquid. Understanding the solubility rules helps predict which compounds will precipitate under given conditions.

Solubility Product Constant (Ksp)

The solubility product constant (Ksp) is an equilibrium constant that quantifies the solubility of a sparingly soluble ionic compound. It is calculated from the concentrations of the ions in a saturated solution at a specific temperature. When the product of the ion concentrations exceeds the Ksp, a precipitate will form, indicating that the solution is supersaturated.

Stoichiometry of Reactions

Stoichiometry involves the calculation of reactants and products in chemical reactions based on balanced chemical equations. In this context, it is essential to determine the moles of KOH and NiSO4 present in the solutions to assess the potential for a reaction and the formation of a precipitate. This allows for the identification of limiting reactants and the amounts of products formed.