Why is calcium carbonate a weak electrolyte, while calcium chloride is a strong electrolyte? (Refer to A.3 and A.4 in the Data Table.) aqueous barium hydroxide, Ba(OH)2, reduce the tweak electrolyte? (Refer to B.3 in the Data Table.) Copyright © 2013 P
The Correct Answer and Explanation is:
Calcium carbonate (CaCO₃) is a weak electrolyte because it has very low solubility in water, meaning it barely dissociates into ions when dissolved. Most of the substance remains as solid particles rather than dissociating completely. As a result, it contributes very few ions to the solution, allowing it to conduct electricity only weakly.
In contrast, calcium chloride (CaCl₂) is a strong electrolyte because it is highly soluble in water and dissociates completely into calcium ions (Ca²⁺) and chloride ions (Cl⁻). This complete dissociation produces a large number of ions in solution, enabling the solution to conduct electricity effectively.
This behavior is summarized by their dissociation tendencies:
- CaCO₃ (s) ⇌ Ca²⁺ (aq) + CO₃²⁻ (aq) (very limited)
- CaCl₂ (s) → Ca²⁺ (aq) + 2Cl⁻ (aq) (complete)
As for barium hydroxide (Ba(OH)₂), it is a strong base that fully dissociates in water to yield two hydroxide ions (OH⁻) per formula unit:
- Ba(OH)₂ (s) → Ba²⁺ (aq) + 2OH⁻ (aq)
When Ba(OH)₂ is added to a solution containing calcium carbonate, it could interact with the carbonate ions. The addition of hydroxide ions shifts equilibria and may slightly increase the solubility of calcium carbonate due to the formation of complex species or changes in pH. However, this effect would not turn calcium carbonate into a strong electrolyte because its inherent low solubility still limits its dissociation.
In summary, electrolyte strength primarily depends on solubility and degree of dissociation. Calcium chloride is a strong electrolyte due to complete dissociation, while calcium carbonate remains weak because it largely stays undissolved. Barium hydroxide, although fully dissociated itself, does not significantly alter the dissociation profile of calcium carbonate.
