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

When calcium chloride (CaCl₂) dissolves in water, it dissociates into its constituent ions as follows: \[ CaCl_2(s) \xrightarrow[]{H_2O} Ca^{2+}(aq) + 2Cl^-(aq) \]

Step-by-step solution

Identify the formula for calcium chloride

Calcium chloride is composed of calcium ions (Ca²⁺) and chloride ions (Cl⁻). The formula for calcium chloride is CaCl₂.

Write the dissolution process in water

When calcium chloride dissolves in water, it dissociates into its constituent ions. The calcium ions and the chloride ions separate and are surrounded by water molecules.

Write the balanced dissociation equation

To show the dissociation of calcium chloride in water, we can write the following balanced equation: \[ CaCl_2(s) \xrightarrow[]{H_2O} Ca^{2+}(aq) + 2Cl^-(aq) \] This equation indicates that one mole of solid calcium chloride (CaCl₂) dissociates into one mole of calcium ions (Ca²⁺) and two moles of chloride ions (Cl⁻) when dissolved in water.

Key concepts

Electrolytes in Chemistry

Electrolytes are substances that, when dissolved in water, produce ions and thus become capable of conducting electricity. They are vital not only for a variety of industrial applications but also for the normal functioning of biological systems. Calcium chloride (\r\( CaCl_2 \)), as mentioned in the exercise, is an example of a strong electrolyte. When dissolved in water, it readily dissociates into its constituent ions, calcium (\r\( Ca^{2+} \)) and chloride (\r\( Cl^- \)), which are charged particles. These ions facilitate the flow of electrical current through the solution. In contrast to strong electrolytes, weak electrolytes partially dissociate in water, resulting in a less conductive solution. Understanding the behavior of electrolytes is crucial for grasping concepts in fields such as chemistry, physics, medicine, and environmental science.

Dissolution Process

The dissolution process refers to the way in which a solid, liquid, or gas forms a solution in a solvent. The most common example is the dissolution of solid salts, like calcium chloride, in water. This process involves the solute (calcium chloride) being surrounded by solvent molecules (water), which leads to the separation of the solute into its individual ions. Each ion becomes surrounded by a sphere of water molecules; a phenomenon known as hydration. These interactions between the solute and solvent reduce the ionic bonds in the solid, allowing it to disperse throughout the solvent and resulting in a homogeneous mixture or solution. It's worth noting that the dissolution of ionic compounds is different from molecular compounds due to the formation of ions in solution, further emphasizing the distinctive nature of electrolytes in chemistry.

Balanced Chemical Equations

In chemistry, a balanced chemical equation is critical for representing the conservation of mass in a reaction. The number of atoms of each element in the reactants must be equal to the number of atoms of those elements in the products. In the case of calcium chloride dissolving in water, the balanced chemical equation is:\r
\r\[ CaCl_2(s) \xrightarrow{H_2O} Ca^{2+}(aq) + 2Cl^-(aq) \]\r
\rThis equation shows one mole of solid calcium chloride (\r\( CaCl_2 \)) dissociating to form one mole of calcium ions and two moles of chloride ions in an aqueous solution. The coefficients—one for the calcium ion and two for the chloride ions—ensure the equation is balanced, with two chloride atoms on each side of the equation. A balanced equation such as this one helps chemists calculate the amount of reactants required and predict the amount of products formed in a chemical reaction.