Carbon dioxide (CO₂)is readily soluble in water, according to the equation CO₂ + H₂O → H₂CO₃. Carbonic acid (H₂CO₃)is a weak acid. If CO₂ is bubbled into a beaker containing pure, freshly-distilled water, which of the following graphs correctly describes the results?

Question

Quizplus · Accepted Answer

When CO₂ is bubbled into water, it forms carbonic acid (H₂CO₃) which can partially dissociate into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻). The increase in the concentration of H⁺ ions leads to a decrease in pH of the solution. The graph in choice C shows a decrease in pH with the addition of CO₂, which is consistent with the process. The other graphs do not show a significant change in pH with the addition of CO₂.

Carbon Dioxide (CO₂)is Readily Soluble in Water, According to the Equation