Question

Write equations showing the ions present after the following strong electrolytes are dissolved in water. a. \(\mathrm{HNO}_{3}\) b. \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) c. \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\) d. \(\mathrm{SrBr}_{2}\) e. \(\mathrm{KClO}_{4}\) f. \(\mathrm{NH}_{4} \mathrm{Br}\) g. \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) h. \(\mathrm{CuSO}_{4}\) i. NaOH

Short answer

a. \(\mathrm{HNO}_{3} \rightarrow \mathrm{H}^{+} + \mathrm{NO}_{3}^{-}\) b. \(\mathrm{Na}_{2} \mathrm{SO}_{4} \rightarrow 2\mathrm{Na}^{+} + \mathrm{SO}_{4}^{2-}\) c. \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3} \rightarrow \mathrm{Al}^{3+} + 3\mathrm{NO}_{3}^{-}\) d. \(\mathrm{SrBr}_{2} \rightarrow \mathrm{Sr}^{2+} + 2\mathrm{Br}^{-}\) e. \(\mathrm{KClO}_{4} \rightarrow \mathrm{K}^{+} + \mathrm{ClO}_{4}^{-}\) f. \(\mathrm{NH}_{4} \mathrm{Br} \rightarrow \mathrm{NH}_{4}^{+} + \mathrm{Br}^{-}\) g. \(\mathrm{NH}_{4} \mathrm{NO}_{3} \rightarrow \mathrm{NH}_{4}^{+} + \mathrm{NO}_{3}^{-}\) h. \(\mathrm{CuSO}_{4} \rightarrow \mathrm{Cu}^{2+} + \mathrm{SO}_{4}^{2-}\) i. \(\mathrm{NaOH} \rightarrow \mathrm{Na}^{+} + \mathrm{OH}^{-}\)

Step-by-step solution

a. Dissociation of \(\mathrm{HNO}_{3}\)#

When \(\mathrm{HNO}_{3}\) dissolves in water, it dissociates into hydrogen ions (\(\mathrm{H}^{+}\)) and nitrate ions (\(\mathrm{NO}_{3}^{-}\)). The equation for the dissociation of \(\mathrm{HNO}_{3}\) is: \(\mathrm{HNO}_{3} \rightarrow \mathrm{H}^{+} + \mathrm{NO}_{3}^{-}\)

b. Dissociation of \(\mathrm{Na}_{2} \mathrm{SO}_{4}\)#

When \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) dissolves in water, it dissociates into two sodium ions (\(\mathrm{Na}^{+}\)) and a sulfate ion (\(\mathrm{SO}_{4}^{2-}\)). The equation for the dissociation of \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) is: \(\mathrm{Na}_{2} \mathrm{SO}_{4} \rightarrow 2\mathrm{Na}^{+} + \mathrm{SO}_{4}^{2-}\)

c. Dissociation of \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\)#

When \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\) dissolves in water, it dissociates into an aluminum ion (\(\mathrm{Al}^{3+}\)) and three nitrate ions (\(\mathrm{NO}_{3}^{-}\)). The equation for the dissociation of \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\) is: \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3} \rightarrow \mathrm{Al}^{3+} + 3\mathrm{NO}_{3}^{-}\)

d. Dissociation of \(\mathrm{SrBr}_{2}\)#

When \(\mathrm{SrBr}_{2}\) dissolves in water, it dissociates into a strontium ion (\(\mathrm{Sr}^{2+}\)) and two bromide ions (\(\mathrm{Br}^{-}\)). The equation for the dissociation of \(\mathrm{SrBr}_{2}\) is: \(\mathrm{SrBr}_{2} \rightarrow \mathrm{Sr}^{2+} + 2\mathrm{Br}^{-}\)

e. Dissociation of \(\mathrm{KClO}_{4}\)#

When \(\mathrm{KClO}_{4}\) dissolves in water, it dissociates into a potassium ion (\(\mathrm{K}^{+}\)) and a perchlorate ion (\(\mathrm{ClO}_{4}^{-}\)). The equation for the dissociation of \(\mathrm{KClO}_{4}\) is: \(\mathrm{KClO}_{4} \rightarrow \mathrm{K}^{+} + \mathrm{ClO}_{4}^{-}\)

f. Dissociation of \(\mathrm{NH}_{4} \mathrm{Br}\)#

When \(\mathrm{NH}_{4} \mathrm{Br}\) dissolves in water, it dissociates into an ammonium ion (\(\mathrm{NH}_{4}^{+}\)) and a bromide ion (\(\mathrm{Br}^{-}\)). The equation for the dissociation of \(\mathrm{NH}_{4} \mathrm{Br}\) is: \(\mathrm{NH}_{4} \mathrm{Br} \rightarrow \mathrm{NH}_{4}^{+} + \mathrm{Br}^{-}\)

g. Dissociation of \(\mathrm{NH}_{4} \mathrm{NO}_{3}\)#

When \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) dissolves in water, it dissociates into an ammonium ion (\(\mathrm{NH}_{4}^{+}\)) and a nitrate ion (\(\mathrm{NO}_{3}^{-}\)). The equation for the dissociation of \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) is: \(\mathrm{NH}_{4} \mathrm{NO}_{3} \rightarrow \mathrm{NH}_{4}^{+} + \mathrm{NO}_{3}^{-}\)

h. Dissociation of \(\mathrm{CuSO}_{4}\)#

When \(\mathrm{CuSO}_{4}\) dissolves in water, it dissociates into a copper ion (\(\mathrm{Cu}^{2+}\)) and a sulfate ion (\(\mathrm{SO}_{4}^{2-}\)). The equation for the dissociation of \(\mathrm{CuSO}_{4}\) is: \(\mathrm{CuSO}_{4} \rightarrow \mathrm{Cu}^{2+} + \mathrm{SO}_{4}^{2-}\)

i. Dissociation of \(\mathrm{NaOH}\)#

When \(\mathrm{NaOH}\) dissolves in water, it dissociates into a sodium ion (\(\mathrm{Na}^{+}\)) and a hydroxide ion (\(\mathrm{OH}^{-}\)). The equation for the dissociation of \(\mathrm{NaOH}\) is: \(\mathrm{NaOH} \rightarrow \mathrm{Na}^{+} + \mathrm{OH}^{-}\)

Key concepts

Chemical Equations

Chemical equations are expressions that capture chemical reactions in a concise way. They show how reactants transform into products, using symbols and formulas to represent these substances. These equations are essential in chemistry because they clearly illustrate the conservation of mass and atoms. In a chemical equation, each molecule or ion is represented by its chemical formula, while the conservation principle ensures the number of each type of atom on the reactant side matches the number on the product side.
To write a balanced chemical equation, it's important to ensure the total charge is the same on both sides. This reflects the principle of charge conservation. Take, for example, the dissociation of sodium sulfate: \[\text{Na}_2\text{SO}_4 \rightarrow 2\text{Na}^+ + \text{SO}_4^{2-}\]This equation shows sodium sulfate in its neutral state dissociating into ions, balancing both mass and charge.

Ionic Compounds

Ionic compounds consist of positive and negative ions held together by ionic bonds, forming a lattice structure. These compounds are typically the result of metal atoms losing electrons and non-metal atoms gaining electrons to achieve stable electron configurations. This electron transfer results in cations (positively charged) and anions (negatively charged).
When ionic compounds dissolve in water, they dissociate into their respective ions. Consider \(\text{CaCl}_2\), which dissociates as: \(\text{CaCl}_2 \rightarrow \text{Ca}^{2+} + 2\text{Cl}^{-}\)In solutions, the ions can move freely, allowing the solution to conduct electricity. This property makes these solutions 'electrolytes'. Strong electrolytes dissociate almost completely, resulting in numerous free ions.

Aqueous Solutions

In chemistry, an aqueous solution is one where water is the solvent, and it plays a crucial role in dissolving ionic compounds. The polar nature of water molecules facilitates the separation and interaction of ions within a solute.
When substances dissolve in water, the solute's ions are surrounded by water molecules. This interaction stabilizes the free ions in the solution. For example, when \(\text{KCl}\) dissolves, it separates into \(\text{K}^+\) and \(\text{Cl}^-\) ions, each encircled by water molecules. The dissolution process in water is vital for many biological and chemical processes, making aqueous solutions an indispensable concept in chemistry.