Question

Write a balanced equation for the dissociation of each of the following strong electrolytes in water: a. \(\mathrm{LiBr}\) b. \(\mathrm{NaNO}_{3}\) c. \(\mathrm{CuCl}_{2}\) d. \(\mathrm{K}_{2} \mathrm{CO}_{3}\)

Short answer

LiBr: \[ \text{LiBr} \rightarrow \text{Li}^{+} + \text{Br}^{-} \] NaNO3: \[ \text{NaNO}_{3} \rightarrow \text{Na}^{+} + \text{NO}_{3}^{-} \] CuCl2: \[ \text{CuCl}_{2} \rightarrow \text{Cu}^{2+} + 2\text{Cl}^{-} \] K2CO3: \[ \text{K}_{2}\text{CO}_{3} \rightarrow 2 \text{K}^{+} + \text{CO}_{3}^{2-} \]

Step-by-step solution

Write the formula for the dissociation of LiBr in water

Lithium bromide (LiBr) dissociates completely in water into lithium ions \(\text{Li}^{+}\) and bromide ions \(\text{Br}^{-}\). The balanced chemical equation is: \[ \text{LiBr (s)} \rightarrow \text{Li}^{+} (\text{aq}) + \text{Br}^{-} (\text{aq}) \]

Write the formula for the dissociation of NaNO3 in water

Sodium nitrate (NaNO3) dissociates completely in water into sodium ions \(\text{Na}^{+}\) and nitrate ions \(\text{NO}_{3}^{-}\). The balanced chemical equation is: \[ \text{NaNO}_{3} (\text{s}) \rightarrow \text{Na}^{+} (\text{aq}) + \text{NO}_{3}^{-} (\text{aq}) \]

Write the formula for the dissociation of CuCl2 in water

Copper(II) chloride (CuCl2) dissociates completely in water into copper ions \(\text{Cu}^{2+}\) and chloride ions \(\text{Cl}^{-}\). The balanced chemical equation is: \[ \text{CuCl}_{2} (\text{s}) \rightarrow \text{Cu}^{2+} (\text{aq}) + 2\text{Cl}^{-} (\text{aq}) \]

Write the formula for the dissociation of K2CO3 in water

Potassium carbonate (K2CO3) dissociates completely in water into potassium ions \(\text{K}^{+}\) and carbonate ions \(\text{CO}_{3}^{2-}\). The balanced chemical equation is: \[ \text{K}_{2}\text{CO}_{3} (\text{s}) \rightarrow 2 \text{K}^{+} (\text{aq}) + \text{CO}_{3}^{2-} (\text{aq}) \]

Key concepts

Balanced Chemical Equations

In chemistry, a balanced chemical equation is crucial for representing a chemical reaction accurately. A balanced equation ensures that the number of atoms for each element is equal on both sides of the reaction.
This follows the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
For example, in the dissociation of lithium bromide (LiBr) in water:
\[\text{LiBr (s)} \rightarrow \text{Li}^{+} (\text{aq}) + \text{Br}^{-} (\text{aq}) \] Each side of the equation has one lithium (Li) atom and one bromine (Br) atom, which makes the equation balanced.
This ensures that we properly account for all atoms present in the reactants and products.

• Always ensure the same number of each type of atom on both sides.
• Use coefficients to balance the equations, not subscripts.

Electrolytes

Electrolytes are substances that dissolve in water to produce conductive solutions of ions. Strong electrolytes, like the ones in this exercise, dissociate completely in water.
This means they break apart into their constituent ions fully when dissolved. For instance, when sodium nitrate (NaNO3) dissolves in water:
\[\text{NaNO}_{3} (\text{s}) \rightarrow \text{Na}^{+} (\text{aq}) + \text{NO}_{3}^{-} (\text{aq}) \] Sodium ions (\text{Na}^{+}) and nitrate ions (\text{NO}_{3}^{-}) are all that remain in the solution.
This complete dissociation is characteristic of strong electrolytes, making their solutions excellent conductors of electricity.

• Electrolytes are crucial for many biological processes.
• In chemistry, they help in conducting electrical currents in solutions.

Aqueous Solutions

An aqueous solution is simply a solution in which water is the solvent. When ionic compounds dissolve in water, they disperse into their respective ions.
For example, potassium carbonate (K₂CO₃) dissolves in water to form:
\[\text{K}_{2}\text{CO}_{3} (\text{s}) \rightarrow 2 \text{K}^{+} (\text{aq}) + \text{CO}_{3}^{2-} (\text{aq}) \] Here, \(\text{K}^{+}\) and \(\text{CO}_{3}^{2-}\) ions are surrounded by water molecules within the solution.
The term 'aqueous' (denoted as \(\text{aq}\) in chemical equations) tells us that the ions are in a water-based solution.

• Aqueous solutions are fundamental in chemical reactions, especially in biological and environmental contexts.
• They are key to understanding many chemical equilibria in a variety of settings.