Question

Write the equation for the dissolution of sodium carbonate in water as found in your laboratory guide.

Na˘2CO˘3 + 2H˘2O —› 2Na^+ + 2OH^- + H˘2CO˘3

When sodium carbonate is dissolved in water, it doesn’t dissociate, or break up, completely. There is always some sodium carbonate in solution. Knowing this, which of the two samples is most alkaline? Explain why you say this.

Answer 1

Na₂CO₃(s) → 2Na⁺(aq) + CO₃²⁻(aq)
The sodium carbonate formed from a strong base and a weak acid. Hydrolysis is subjected to the anion of a weak acid.

CO₃²⁻ + H₂O ⇄ HCO₃⁻ + OH⁻
HCO₃⁻ + H₂O ⇄ H₂CO₃ + OH⁻

pH>7 alkaline solution

2Na⁺ + CO₃²⁻ + 2H₂O ⇄ 2Na⁺ + 2OH⁻ + H₂CO₃