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 dissolution of calcium chloride (CaCl₂) in water can be represented by the balanced chemical equation: \[ CaCl_{2}(s) \xrightarrow{H_2O} Ca^{2+}(aq) + 2Cl^-(aq) \] This equation shows the solid calcium chloride dissociating into its ions, calcium (Ca²⁺) and chloride (Cl⁻), in an aqueous solution.

Step-by-step solution

Understanding electrolytes

An electrolyte is a substance that produces ions when dissolved in water. These ions allow the solution to conduct electricity. In this case, calcium chloride is a strong electrolyte, which means it completely dissociates into its ions when dissolved in water.

Identifying the components of calcium chloride

Calcium chloride is made up of calcium ions (Ca²⁺) and chloride ions (Cl⁻). The chemical formula for calcium chloride is CaCl₂. This indicates that one calcium ion combines with two chloride ions to form one formula unit of calcium chloride.

Writing the balanced chemical equation for dissolution

Now, we can write the balanced chemical equation that shows the dissolution of calcium chloride in water. To do this, we will represent the reactants (calcium chloride and water) and the products (calcium ions and chloride ions) in the form of a balanced equation: \[ CaCl_{2}(s) \xrightarrow{H_2O} Ca^{2+}(aq) + 2Cl^-(aq) \] Here, "(s)" denotes the solid state of calcium chloride, "(aq)" indicates the aqueous state of the ions, and "H₂O" in the arrow represents the solvent in which the dissolution occurs. The balanced equation shows that one formula unit of calcium chloride dissociates into one calcium ion and two chloride ions when dissolved in water.

Key concepts

Calcium Chloride

Calcium chloride is a white crystalline salt with the chemical formula \(CaCl_2\). It's commonly used for de-icing roads and sidewalks during winter because it can effectively lower the freezing point of water. When calcium chloride is spread over ice or snow, it helps to melt them by absorbing moisture and heat from the environment. This process, known as exothermic reaction, generates additional heat to melt the ice faster.
It is also widely used in various industries, including food manufacturing, as a drying agent, and in swimming pool maintenance to increase water hardness.
Understanding calcium chloride's chemical properties and behaviors is essential for maximizing its effectiveness in its many applications.

Dissolution Reaction

A dissolution reaction occurs when a solid substance dissolves in a solvent, commonly water, to form a solution. In the case of calcium chloride, the dissolution involves the separation of its constituent ions as it interacts with water.
During this process, water molecules surround and interact with the calcium chloride particles, breaking the ionic bonds between the calcium and chloride ions. This leads to the complete dissociation of calcium chloride into its ions.
The success of a dissolution reaction depends on several factors like the temperature of the water and the solubility of the substance. With calcium chloride being highly soluble, it dissolves rather quickly, making it efficient for applications such as de-icing.

Ions

Ions are charged particles that are formed when atoms or molecules gain or lose electrons. In the context of calcium chloride, when it dissolves in water, it breaks apart into two types of ions: calcium ions and chloride ions.

• Calcium ions \((Ca^{2+})\) carry a positive charge because they lose two electrons.
• Chloride ions \((Cl^-)\) carry a negative charge because each one gains an electron.

These ions are crucial for conducting electricity in the solution. Since calcium chloride is a strong electrolyte, it means that the dissolution results in a complete breakdown into ions, which enhances its conductivity.
Understanding ions is key in grasping how substances dissolve and interact within a solution.

Chemical Equation

A chemical equation is a symbolic representation of a chemical reaction. For the dissolution of calcium chloride, the equation highlights how molecules and ions are transformed during the process.
The equation for this reaction can be written as: \[CaCl_{2}(s) \xrightarrow{H_2O} Ca^{2+}(aq) + 2Cl^-(aq)\]The term \((s)\) indicates solid calcium chloride before it dissolves, and \((aq)\) indicates the ions in an aqueous solution after dissolution.
Writing and balancing chemical equations are fundamental skills in chemistry as they provide a detailed view of the molecular changes occurring during reactions. This particular equation shows one formula unit of solid calcium chloride yielding one calcium ion and two chloride ions upon dissolving.