What is the primary chemical found in water at a pH of 4.3?

A pH of 4.3 indicates that the water is acidic. In an acidic environment, carbon dioxide plays a significant role as it dissolves in water to form carbonic acid (H2CO3). This, in turn, dissociates to release hydrogen ions (H+) and bicarbonate ions (HCO3-), influencing the pH level.

At a lower pH, the concentration of dissolved CO2 increases due to its solubility in water. Consequently, carbon dioxide is a dominant species in acidic conditions. While bicarbonate is present as well, it generally becomes more prominent under neutral to alkaline conditions. Hydroxide ions would be scarce in such acidic conditions, and carbonate ions typically appear in greater concentrations at higher pH levels, where the environment is more alkaline. Thus, the presence of carbon dioxide is critical in explaining the chemistry behind a pH of 4.3.