Problem 19 - Chemistry and Chemical Reactivity

Question

Dissolving \(\mathrm{K}_{2} \mathrm{CO}_{3}\) in water gives a basic solution. Write a balanced equation showing how this salt can produce a basic solution.

Step-by-Step Solution

Answer

The solution is basic due to the carbonate ion (\(\mathrm{CO}_{3}^{2-}\)).

Step 1: Dissociation of Potassium Carbonate

Potassium carbonate (\(\mathrm{K}_{2} \mathrm{CO}_{3}\)) dissociates in water into potassium ions (\(\mathrm{K}^+\)) and carbonate ions (\(\mathrm{CO}_{3}^{2-}\)). The equation for this process is:\[\mathrm{K}_{2}\mathrm{CO}_{3} (s) \rightarrow 2\mathrm{K}^+ (aq) + \mathrm{CO}_{3}^{2-} (aq) \]

Key Concepts

Ions in Solution

When a salt dissolves in water, it separates into its respective ions, allowing these ions to roam freely in the solution. This process of forming ions in a solution is known as dissociation. The ions in the solution are essential because they dictate the properties of the solution, including its conductivity and reactivity. For example, in the dissolution of potassium carbonate \(\mathrm{K}_2\mathrm{CO}_3\), the salt dissociates into potassium ions \(\mathrm{K}^+\) and carbonate ions \(\mathrm{CO}_3^{2-}\). These ions can then participate in further chemical reactions or influence the pH of the solution.

• Potassium ions (\(\mathrm{K}^+\)): These are positively charged ions that help in increasing the conductivity of the solution.
• Carbonate ions (\(\mathrm{CO}_3^{2-}\)): As negatively charged ions, they can react with water to influence the acidity or basicity of the solution.

Understanding ions in solution is fundamental in chemistry because it helps predict the behavior of the solution when conditions change. When salts dissolve, the resulting free ions affect the solution’s chemical and physical properties, setting the stage for potential reactions, like the formation of a basic solution.

K2CO3 Dissolution

The dissolution of potassium carbonate, \(\mathrm{K}_2\mathrm{CO}_3\), is an essential process in understanding how salts can produce basic solutions. When \(\mathrm{K}_2\mathrm{CO}_3\) is added to water, it separates into \(2\) potassium ions and one carbonate ion. The dissociation equation is as follows:\[\mathrm{K}_{2}\mathrm{CO}_{3} (s) \rightarrow 2\mathrm{K}^+ (aq) + \mathrm{CO}_{3}^{2-} (aq) \]This process shows how simple ionic compounds break down in water.
The carbonate ions, \(\mathrm{CO}_3^{2-}\), are particularly significant here. They can react with water molecules to form bicarbonate and hydroxide ions, increasing the solution’s pH and making it basic.

• Carbonate ion reaction: The interaction of \(\mathrm{CO}_3^{2-}\) with \(\mathrm{H}_2\mathrm{O}\) plays a crucial role in altering the water's pH level.

Hence, the dissolution of \(\mathrm{K}_2\mathrm{CO}_3\) not only shows basic decomposition of salts but also the potential for reactions that alter the solution's chemical environment.

Equation Balancing

Balancing chemical equations is a critical skill in chemistry that ensures the law of conservation of mass is followed. This means that the number of atoms of each element should be the same on both sides of the equation. When writing the equation for the dissociation of \(\mathrm{K}_2\mathrm{CO}_3\), it is crucial to maintain balance.
The given equation already illustrates this balance:\[\mathrm{K}_{2}\mathrm{CO}_{3} (s) \rightarrow 2\mathrm{K}^+ (aq) + \mathrm{CO}_{3}^{2-} (aq) \]

• Two Potassium ions (\(\mathrm{K}^+\)): Notably, two \(\mathrm{K}^+\) ions confirm balance for potassium.
• One Carbonate ion (\(\mathrm{CO}_3^{2-}\)): Carbon and oxygen are accounted for by the presence of \(\mathrm{CO}_3^{2-}\).

Balancing equations is not just necessary for stoichiometry; it helps predict the amount of product formed and the trend seen in reaction dynamics, which is essential for understanding and performing chemical reactions accurately.