Question

Biological Oceanography

10. (a) What happens equations you learned in class to to the pH when CO2 is added to seawater? Provide the two equilibrium justify your answer (2 points) (b) Looking at your equations above explain what happens to added to sea water (1 point) carbonate ions when CO2 is (c) What happens down the equation for Q to justify your answer (2 points) to the carbon saturation state (2) when CO2 is added to seawater? Write

Answer 1

Answer a)

1. When more CO2 is added to the seawater, the pH of the water falls down becoming acidic.
2. Reaction:-

CO₂ + H₂O --> H₂CO₃

In this reaction, the carbon dioxide reacts with water to produce carbonic acid which in turn makes the water acidic. In short, it decreases the pH of sea water.

H₂CO₃ --> H⁺ + HCO^{​​​​​​}₃^-

The carbonic acid splits to form free hydrogen ions and bicarbonate ions which in turn determines the further reaction. These are stated to be the two equilibrium reactions satisfying the answer. Carbonic acid is responsible for increasing acidity and thus decreasing pH.