Question

Show how each of the following strong electrolytes "breaks up" into its component ions upon dissolving in water by drawing molecular-level pictures. a. \(\mathrm{NaBr}\) f. \(\mathrm{FeSO}_{4}\) b. \(\mathrm{MgCl}_{2}\) g. \(\mathrm{KMnO}_{4}\) c. \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\) h. \(\mathrm{HClO}_{4}\) d. \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}\) i. \(\mathrm{NH}_{4} \mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) (ammonium acetate) e. \(\mathrm{NaOH}\)

Short answer

a. NaBr(s) -> Na+(aq) + Br-(aq) b. MgCl2(s) -> Mg2+(aq) + 2Cl-(aq) c. Al(NO3)3(s) -> Al3+(aq) + 3NO3-(aq) d. (NH4)2SO4(s) -> 2NH4+(aq) + SO42-(aq) e. NaOH(s) -> Na+(aq) + OH-(aq) f. FeSO4(s) -> Fe2+(aq) + SO42-(aq) g. KMnO4(s) -> K+(aq) + MnO4-(aq) h. HClO4(aq) -> H+(aq) + ClO4-(aq) i. NH4C2H3O2(s) -> NH4+(aq) + C2H3O2-(aq)

Step-by-step solution

a. Sodium Bromide (NaBr) Dissociation

Sodium bromide is an ionic compound, which dissociates into sodium ions (\(\mathrm{Na^{+}}\)) and bromide ions (\(\mathrm{Br^{-}}\)) in water. NaBr(s) -> Na+(aq) + Br-(aq)

b. Magnesium Chloride (MgCl2) Dissociation

Magnesium Chloride is an ionic compound, which dissociates into magnesium ions (\(\mathrm{Mg^{2+}}\)) and chloride ions (\(\mathrm{Cl^{-}}\)) in water. MgCl2(s) -> Mg2+(aq) + 2Cl-(aq)

c. Aluminum Nitrate [Al(NO3)3] Dissociation

Aluminum nitrate is an ionic compound, which dissociates into aluminum ions (\(\mathrm{Al^{3+}}\)) and nitrate ions (\(\mathrm{NO_3^{-}}\)) in water. Al(NO3)3(s) -> Al3+(aq) + 3NO3-(aq)

d. Ammonium Sulfate [(NH4)2SO4] Dissociation

Ammonium sulfate is an ionic compound, which dissociates into ammonium ions (\(\mathrm{NH_4^{+}}\)) and sulfate ions (\(\mathrm{SO_4^{2-}}\)) in water. (NH4)2SO4(s) -> 2NH4+(aq) + SO42-(aq)

e. Sodium Hydroxide (NaOH) Dissociation

Sodium hydroxide is an ionic compound, which dissociates into sodium ions (\(\mathrm{Na^{+}}\)) and hydroxide ions (\(\mathrm{OH^{-}}\)) in water. NaOH(s) -> Na+(aq) + OH-(aq)

f. Iron(II) Sulfate (FeSO4) Dissociation

Iron(II) sulfate is an ionic compound, which dissociates into iron(II) ions (\(\mathrm{Fe^{2+}}\)) and sulfate ions (\(\mathrm{SO_4^{2-}}\)) in water. FeSO4(s) -> Fe2+(aq) + SO42-(aq)

g. Potassium Permanganate (KMnO4) Dissociation

Potassium permanganate is an ionic compound, which dissociates into potassium ions (\(\mathrm{K^{+}}\)) and permanganate ions (\(\mathrm{MnO_4^{-}}\)) in water. KMnO4(s) -> K+(aq) + MnO4-(aq)

h. Perchloric Acid (HClO4) Dissociation

Perchloric acid is a strong acid, which dissociates into hydrogen ions (\(\mathrm{H^{+}}\)) and perchlorate ions (\(\mathrm{ClO_4^{-}}\)) in water. HClO4(aq) -> H+(aq) + ClO4-(aq)

i. Ammonium Acetate (NH4C2H3O2) Dissociation

Ammonium acetate is an ionic compound, which dissociates into ammonium ions (\(\mathrm{NH_4^{+}}\)) and acetate ions (\(\mathrm{C_2H_3O_2^{-}}\)) in water. NH4C2H3O2(s) -> NH4+(aq) + C2H3O2-(aq)

Key concepts

Strong Electrolytes

When considering substances that dissolve in water, strong electrolytes are compounds that completely dissociate into ions. What makes electrolytes 'strong' is their ability to conduct electricity in water due to the presence of free-moving ions. This concept is integral for students understanding reactions in solution and electricity conduction in liquids.

Ionic compounds, such as sodium chloride (NaCl) and magnesium chloride (MgCl₂), as well as strong acids like hydrochloric acid (HCl), are examples of strong electrolytes. These compounds are crucial in various industries and biological systems for their conductive properties.

Dissolving in Water

The process of dissolving in water refers to the way substances integrate into water, forming a homogeneous solution. Solubility, which is the measure of how well a substance can dissolve in a solvent, is a key concept for students to understand. Ionic compounds, when dissolved in water, separate into their constituent ions in a process that is crucial for many biological and chemical phenomena.

For instance, table salt (NaCl) dissolves in water by detaching into sodium (Na⁺) and chloride (Cl^-) ions. As educators, we emphasize the importance of this behavior not only for chemical reactions but also in our daily life, like in the salinity of ocean water.

Molecular-Level Illustrations

Visual representations, or molecular-level illustrations, are powerful tools for understanding chemical processes. They help students visualize how particles interact at the molecular level. For the dissolution of ionic compounds, diagrams demonstrate how the ionic lattice breaks apart into individual cations and anions surrounded by water molecules.

These illustrations should depict ions dispersing into the solvent and water molecules orienting themselves around the ions based on charge—oxygen towards cations and hydrogen towards anions. This is vital for demonstrating the hydration shell formation and for explaining concepts like solvation and ion-dipole forces.

Ion Formation

Ion formation is the process by which atoms or molecules gain or lose electrons to form ions, typically when dissolving ionic compounds in water. The generation of positive cations and negative anions is an aspect of chemistry that is fundamental to understanding not only solutions but also various other chemical reactions and biological processes.

An educational focus lies on the ionization energy and electron affinity which influence how likely an atom is to form an ion. Consider sodium's propensity to donate an electron to form Na⁺ and chlorine's tendency to accept an electron to form Cl^-. It's important to demonstrate the role of water in stabilizing these ions by solvation, which facilitates ionic compounds dissolving in water.