Question

Define salt hydrolysis. Explain the hydrolysis of potassium carbonate by giving ionic equations.

Short answer

Answer: When potassium carbonate undergoes hydrolysis in water, the solution becomes more basic due to the increase in hydroxide ion (OH⁻) concentration. This occurs as the carbonate ion (CO₃²⁻) reacts with water molecules, forming bicarbonate ion (HCO₃⁻) and hydroxide ion (OH⁻).

Step-by-step solution

Define Salt Hydrolysis

Salt hydrolysis is a process in which a salt's ions interact with water molecules to form new compounds, resulting in a change in pH. This process typically occurs when an acidic or basic salt dissociates in water, causing the water molecules to either donate or accept protons, thus effectively altering the acidity or alkalinity of the solution.

Identify the ions in potassium carbonate

Potassium carbonate (K₂CO₃) is an ionic compound formed by the combination of two potassium ions (K⁺) and one carbonate ion (CO₃²⁻) in a crystal lattice. When dissolved in water, potassium carbonate dissociates into its individual ions: 2K⁺ and CO₃²⁻.

Write the hydrolysis ionic equations

When potassium carbonate is dissolved in water, the ions interact with water molecules. The potassium ions do not hydrolyze because they come from a strong base (potassium hydroxide, KOH) and do not react with water. However, the carbonate ion (CO₃²⁻) undergoes hydrolysis by accepting protons from water molecules: CO₃²⁻(aq) + H₂O(l) ⇌ HCO₃⁻(aq) + OH⁻(aq) In this reaction, the carbonate ion (CO₃²⁻) picks up a hydrogen ion (H⁺) from water, forming bicarbonate ion (HCO₃⁻) and hydroxide ion (OH⁻). The above equation shows that the hydrolysis of carbonate ion results in an increase in hydroxide ion concentration, causing the solution to become more basic.