Question 10
Calcium carbonate is present in the skeleton of corals. It is formally insoluble in water but a small amount of it is actually in equilibrium between dissolved and undissolved states: CaCO₃ (s) ⇌ Ca²⁺ (aq) CO₃²⁻ (aq) Further, carbonate ions may form carbonic acid in the presence of hydride ions. The former can then decompose to water and carbon dioxide: CO₃²⁻ (aq) + H⁺ (aq) → H₂CO₃ (aq) → CO₂ (aq) + H₂O (l) The balance of these reactions is therefore important for the health of corals and thus of the ocean. Which of the following favors the disintegration of coral skeletons?
A. Acid rain
B. Additional mineral calcium ions in the ocean
C. Higher water alkalinity
D. More dissolved carbon dioxide in the ocean
Editorial review: explain the evidence and whether the original wording gives a unique answer.
A. Acid rain
B. Additional mineral calcium ions in the ocean
C. Higher water alkalinity
D. More dissolved carbon dioxide in the ocean
Editorial review: explain the evidence and whether the original wording gives a unique answer.