Question

Calcium chloride is a strong electrolyte and is used to “salt” streets in the winter to melt ice and snow. Write a reaction to show how this substance breaks apart when it dissolves in water

Short answer

The dissociation of calcium chloride (CaCl₂) in water can be represented by the balanced chemical equation: CaCl₂ (s) → Ca²⁺ (aq) + 2Cl⁻ (aq). This shows that one molecule of solid calcium chloride dissociates into one calcium ion (Ca²⁺) and two chloride ions (Cl⁻) when dissolved in water.

Step-by-step solution

Identify the ions in calcium chloride

In a calcium chloride molecule, there is one calcium ion (Ca²⁺) and two chloride ions (Cl⁻). When calcium chloride dissociates, these ions will separate.

Write the balanced chemical equation for the dissociation of calcium chloride

Now we will write the balanced chemical equation for the dissociation of calcium chloride in water: CaCl₂ (s) → Ca²⁺ (aq) + 2Cl⁻ (aq) In this equation, (s) indicates that calcium chloride is in the solid-state, and (aq) means the ions are dissolved in water. The balanced chemical equation shows that one molecule of solid calcium chloride dissociates into one calcium ion and two chloride ions when dissolved in water.

Key concepts

Understanding Calcium Chloride

Calcium chloride is a common chemical compound with the formula \( \text{CaCl}_2 \). It consists of one calcium ion (Ca²⁺) and two chloride ions (Cl⁻). This compound is often used for de-icing streets because it releases heat when dissolving in water, helping to melt ice. It's known for being highly soluble, which means it dissolves easily in water, releasing its component ions.

The Role of Electrolytes

Electrolytes are substances that, when dissolved in water, produce a solution that can conduct electricity. Calcium chloride is categorized as a strong electrolyte because, upon dissolving, it fully dissociates into its ions. Strong electrolytes like calcium chloride enhance the electrical conductivity of solutions. This dissociation into ions is key to their function, as the presence of free-moving charged particles enables the conduction of electricity.

Writing a Chemical Equation for Dissolution

A chemical equation represents a chemical reaction where substances change to form new compounds. For calcium chloride dissolving in water, we use a dissociation equation. This shows ions separating in a balanced manner. The equation is: \[ \text{CaCl}_2 \,(s) \rightarrow \text{Ca}^{2+} \,(aq) + 2\text{Cl}^- \,(aq) \]Here, \( (s) \) indicates that the calcium chloride is solid, whereas \( (aq) \) signifies the ions are aqueous, meaning they are dispersed in water.

Nature of Ionic Compounds

Ionic compounds like calcium chloride consist of positive and negative ions held together by strong electrostatic forces. In \( \text{CaCl}_2 \), the positive calcium ions and negative chloride ions form a crystalline lattice structure. When the compound dissolves in water, these ions separate, resulting from water molecules overcoming these ionic bonds. This dissolution process makes ionic compounds effective electrolytes, assisting in various reactions and applications.