Question

When CO₂ dissolves in the oceans, it ________.

1) decreases the acidity of the seawater
2) forms an acid that dissolves the shells of sea creatures
3) raises the temperature of the ocean
4) reacts with Ca⁽²⁺⁾ ions to form CaCO₃

Answer 1

When CO₂ dissolves in the ocean, it increases the acidity of seawater by forming carbonic acid, which lowers the pH and hinders the ability of marine organisms to build their calcium carbonate exoskeletons.

Step-by-step explanation:

When CO₂ dissolves in the ocean, it forms carbonic acid which subsequently dissociates to form bicarbonate and hydrogen ions, increasing the concentration of hydrogen ions (H+) in the ocean. This process leads to ocean acidification, lowering the pH of seawater and making it more acidic.

As the acidity increases, it becomes more difficult for marine organisms, such as corals and shellfish, to perform calcification, which is essential for building their calcium carbonate (CaCO₃) structures, such as shells and skeletons. In summary, CO₂ in the atmosphere that dissolves in ocean waters lowers the pH and increases the acidity of the oceans, thus interfering with the organisms' ability to produce their hard exoskeletons made of calcium carbonate.