Consider the reaction between carbon dioxide and water to form carbonic acid (CH2O3):

CO2(𝑔)+H2O(𝑙)⇌CH2O3(𝑎𝑞)

In the ocean, carbonic acid immediately dissociates to form a proton and bicarbonate ion, as follows:

CH2O3(𝑎𝑞)⇌CHO3−(𝑎𝑞)+H+(𝑎𝑞)

As atmospheric CO2 increases, the ocean absorbs more of the gas. Would this sequence of reactions be driven to the left or the right? How would this affect the pH of the ocean?

Verified step by step guidance

1. Identify the sequence of reactions: First, CO2 reacts with H2O to form carbonic acid (CH2O3). Then, carbonic acid dissociates into bicarbonate ion (CHO3−) and a proton (H+).
2. Understand Le Chatelier's Principle, which states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change.
3. Consider the effect of increasing atmospheric CO2: As more CO2 dissolves in the ocean, it shifts the first reaction (CO2 + H2O ⇌ CH2O3) to the right, producing more carbonic acid.
4. Analyze the impact on the second reaction: With more carbonic acid being formed, the reaction (CH2O3 ⇌ CHO3− + H+) is also driven to the right, resulting in increased production of bicarbonate ions and protons.
5. Evaluate the effect on ocean pH: The increase in protons (H+) in the ocean lowers the pH, making the ocean more acidic.