Question

Decide whether a precipitate will form when the following solutions are mixed. If a precipitate forms, write a net ionic equation for the reaction. (a) potassium nitrate and magnesium sulfate (b) silver nitrate and potassium carbonate (c) ammonium carbonate and cobalt(III) chloride (d) sodium phosphate and barium hydroxide (e) barium nitrate and potassium hydroxide

Short answer

If so, write the net ionic equation for the reaction. a) potassium nitrate and magnesium sulfate b) silver nitrate and potassium carbonate c) ammonium carbonate and cobalt(III) chloride d) sodium phosphate and barium hydroxide e) barium nitrate and potassium hydroxide Answer: a) No precipitate will form. b) Yes, a precipitate of silver carbonate (Ag2CO3) will form. The net ionic equation is: 2 Ag+ + CO3 2- -> Ag2CO3↓ c) Yes, a precipitate of cobalt(III) carbonate (Co2(CO3)3) will form. The net ionic equation is: 2 CO3 2- + 3 Co3+ -> Co2(CO3)3↓ d) Yes, a precipitate of barium phosphate (Ba3(PO4)2) will form. The net ionic equation is: 2 PO4 3- + 3 Ba2+ -> Ba3(PO4)2↓ e) No precipitate will form.

Step-by-step solution

Identify the ions in the solutions

The ions in the solutions are potassium ion (K+) and nitrate ion (NO3-) from potassium nitrate (KNO3), and magnesium ion (Mg2+) and sulfate ion (SO4 2-) from magnesium sulfate (MgSO4).

Check solubility of possible products

For the combination of the ions, we can form two possible products: potassium sulfate (K2SO4) and magnesium nitrate (Mg(NO3)2). To determine their solubility, we can refer to a solubility table. Both potassium compounds and nitrates are highly soluble; therefore, both products are soluble.

Determine if a precipitate forms

Since both products are soluble, no precipitate will form when potassium nitrate and magnesium sulfate solutions are mixed. #b)

Identify the ions in the solutions

The ions in the solutions are silver ion (Ag+) and nitrate ion (NO3-) from silver nitrate (AgNO3), and potassium ion (K+) and carbonate ion (CO3 2-) from potassium carbonate (K2CO3).

Check solubility of possible products

For the combination of the ions, we can form two possible products: silver carbonate (Ag2CO3) and potassium nitrate (KNO3). Silver carbonate is insoluble while potassium nitrate is soluble.

Write the net ionic equation for the reaction

Since silver carbonate is insoluble, a precipitate will form. The balanced molecular equation is: 2 AgNO3 + K2CO3 -> Ag2CO3 + 2 KNO3 The net ionic equation is: 2 Ag+ + CO3 2- -> Ag2CO3↓ #c)

Identify the ions in the solutions

The ions in the solutions are ammonium ion (NH4+) and carbonate ion (CO3 2-) from ammonium carbonate (NH4)2CO3), and cobalt(III) ion (Co3+) and chloride ion (Cl-) from cobalt(III) chloride (CoCl3).

Check solubility of possible products

For the combination of the ions, we can form two possible products: cobalt(III) carbonate (Co2(CO3)3) and ammonium chloride (NH4Cl). Cobalt(III) carbonate is insoluble while ammonium chloride is soluble.

Write the net ionic equation for the reaction:eq

Since cobalt(III) carbonate is insoluble, a precipitate will form. The balanced molecular equation is: 2 (NH4)2CO3 + 3 CoCl3 -> Co2(CO3)3 + 6 NH4Cl The net ionic equation is: 2 CO3 2- + 3 Co3+ -> Co2(CO3)3↓ #d)

Identify the ions in the solutions

The ions in the solutions are sodium ion (Na+) and phosphate ion (PO4 3-) from sodium phosphate (Na3PO4), and barium ion (Ba2+) and hydroxide ion (OH-) from barium hydroxide (Ba(OH)2).

Check solubility of possible products

For the combination of the ions, we can form two possible products: barium phosphate (Ba3(PO4)2) and sodium hydroxide (NaOH). Barium phosphate is insoluble while sodium hydroxide is soluble.

Write the net ionic equation for the reaction

Since barium phosphate is insoluble, a precipitate will form. The balanced molecular equation is: 2 Na3PO4 + 3 Ba(OH)2 -> Ba3(PO4)2 + 6 NaOH The net ionic equation is: 2 PO4 3- + 3 Ba2+ -> Ba3(PO4)2↓ #e)

Identify the ions in the solutions

The ions in the solutions are barium ion (Ba2+) and nitrate ion (NO3-) from barium nitrate (Ba(NO3)2), and potassium ion (K+) and hydroxide ion (OH-) from potassium hydroxide (KOH).

Check solubility of possible products

For the combination of the ions, we can form two possible products: barium hydroxide (Ba(OH)2) and potassium nitrate (KNO3). Both products are soluble.

Determine if a precipitate forms

Since both products are soluble, no precipitate will form when barium nitrate and potassium hydroxide solutions are mixed.

Key concepts

Precipitation Reactions

Precipitation reactions are a cornerstone of chemistry, playing a crucial role in various processes, from industrial manufacturing to the inner workings of our bodies. At its core, a precipitation reaction occurs when two soluble salts react in solution to produce at least one insoluble compound—known as a precipitate. This process can be visually fascinating as the precipitate emerges as a solid from the liquid mixture.

Understanding precipitation reactions involves recognizing patterns of solubility. For example, in the reaction between silver nitrate and potassium carbonate, silver carbonate—the precipitate—forms because it is insoluble. Most carbonates, with the exception of those formed with alkali metals and ammonium ion, tend to be insoluble. Being familiar with these patterns empowers students to predict the outcomes of chemical interactions with confidence.

Net Ionic Equations

Delving deeper into the realm of chemistry, net ionic equations provide a more focused view of a chemical reaction. These simplified equations strip away the spectator ions—those that do not participate in the reaction—showcasing only the ions directly involved in forming the precipitate. For instance, in the reaction between silver nitrate and potassium carbonate which produces silver carbonate, the net ionic equation is 2 Ag+ + CO3 2- -> Ag2CO3↓. It succinctly represents the essence of the chemical reaction without the potassium and nitrate ions that remain in solution.

Why Use Net Ionic Equations?

Net ionic equations are particularly valuable for understanding the actual chemical changes taking place. They highlight the active participants, allowing students to focus on the crucial changes during a reaction. Learning to write these equations sharpens problem-solving skills and enhances conceptual clarity.

Soluble and Insoluble Compounds

Chemistry often feels like a puzzle, one where the solubility rules are vital pieces. Soluble compounds dissolve in a solvent, leaving no visible trace, while insoluble compounds remain undissolved, sometimes forming a visible precipitate. These properties are not arbitrary but follow specific rules that help predict solubility.

For instance, nitrates and most compounds of alkali metals are generally soluble, which informs us that, in the mixture of potassium nitrate and magnesium sulfate, no precipitate forms since all the possible products are soluble. Conversely, compounds like silver carbonate are typically insoluble, which is why a precipitate forms when silver nitrate reacts with potassium carbonate.

Importance in Reactions

A deeper understanding of these rules is crucial in chemistry. It aids in anticipating the outcome of reactions, crucial for applications ranging from waste treatment to pharmaceutical development. By mastering the rules of solubility, students develop a toolkit that translates beyond the classroom into real-world problem-solving.