Question

The pH of the solution is directly proportional to the carbonate concentration when added to the solution.

(a) True

(b) False

I got this question by my college director while I was bunking the class.

I need to ask this question from Buffers topic in portion Introduction to Fermentation Processes & Media for Industrial Fermentation of Bioprocess Engineering

Answer 1

The correct answer is:

(b) False

The pH of a solution is not directly proportional to the carbonate concentration when carbonate is added. This is because the pH of a solution depends on the balance between the concentrations of hydrogen ions (H⁺) and hydroxide ions (OH⁻), and carbonate (CO₃²⁻) ions can participate in a buffering system by interacting with carbonic acid (H₂CO₃).

In a typical carbonate buffering system (e.g., in a fermentation medium), the carbonate ion (CO₃²⁻) can react with water to form bicarbonate (HCO₃⁻) and hydroxide ions, which affects the pH. However, the relationship between pH and carbonate concentration is more complex due to this buffering equilibrium.

Thus, pH and carbonate concentration are related but not directly proportional, as the buffering capacity and the pH depend on several factors, including the concentration of other species in the solution (like carbonic acid and bicarbonate).