An aqueous solution of sodium carbonate is alkaline because sodium carbonate is a salt of — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

# Why Sodium Carbonate Solution is Alkaline **Step 1: Identify the salt components** $Na_2CO_3$ is a salt formed from: - Strong base: $NaOH$ - Weak acid: $H_2CO_3$ **Step 2: Analyze hydrolysis** When $Na_2CO_3$ dissolves in water, the carbonate ion undergoes hydrolysis: $$CO_3^{2-} + H_2O \rightleftharpoons HCO_3^- + OH^-$$ **Step 3: Determine pH effect** - The hydrolysis of $CO_3^{2-}$ produces $OH^-$ ions, making the solution basic - $Na^+$ ions do not hydrolyze (from strong base) **Step 4: Conclusion** $Na_2CO_3$ is a salt of a **strong base and weak acid**. According to salt hydrolysis rules: - Salt of strong base + weak acid → **alkaline solution** ✓ - (The anion of the weak acid accepts protons, releasing $OH^-$) **Answer: C — strong base and weak acid**