Write a molecular equation for the precipitation reaction that occurs (if any) when each pair of aqueous solutions is mixed. If no reaction occurs, write 'NO REACTION.' c. copper(II) nitrate and magnesium sulfide

Verified step by step guidance

1. Identify the ions present in each compound: Copper(II) nitrate (Cu(NO_3)_2) dissociates into Cu^{2+} and NO_3^- ions, while magnesium sulfide (MgS) dissociates into Mg^{2+} and S^{2-} ions.
2. Determine the possible products by swapping the ions: The potential products are copper(II) sulfide (CuS) and magnesium nitrate (Mg(NO_3)_2).
3. Check the solubility of the potential products: Refer to solubility rules to determine if any of the products are insoluble. Copper(II) sulfide (CuS) is insoluble in water, while magnesium nitrate (Mg(NO_3)_2) is soluble.
4. Write the balanced molecular equation for the reaction: Cu(NO_3)_2(aq) + MgS(aq) \rightarrow CuS(s) + Mg(NO_3)_2(aq).
5. Conclude that a precipitation reaction occurs because CuS is an insoluble solid that precipitates out of the solution.

Key Concepts

Precipitation Reactions

Precipitation reactions occur when two aqueous solutions react to form an insoluble solid, known as a precipitate. This process typically involves the exchange of ions between the reactants, leading to the formation of a compound that is not soluble in water. Identifying whether a precipitate forms requires knowledge of solubility rules, which dictate the solubility of various ionic compounds in water.

Molecular Equations

A molecular equation represents the reactants and products of a chemical reaction in their molecular forms, without showing the dissociation of ions in solution. In the context of precipitation reactions, the molecular equation provides a clear depiction of the substances involved before and after the reaction, allowing for easier identification of the precipitate formed, if any.

Solubility Rules

Solubility rules are guidelines that help predict whether a particular ionic compound will dissolve in water. These rules indicate which combinations of cations and anions will result in soluble or insoluble products. For example, most sulfides are insoluble except for those of alkali metals and alkaline earth metals, which is crucial for determining the outcome of the reaction between copper(II) nitrate and magnesium sulfide.