L2_lo [30 10.3 4.4 LoY High pH buffer Low pH buffer IoD 4.0 ho_2 4.0 Nes Nes Questions and Problems Q4 Which solution(s) showed the greatest change in pH? Hz0 014 AlCl solution Should 4gr ?.XtY} change both solutions and Qr € not buffers; PH because both Q5 Which solution(s) showed little or no change in pH? Why? Buffer solution showed little or no change in pH. The low pH buffer showed minimum pH change due to the absence of acid or base. pH does not change because the storage of acids does not change much. Normally, the pH of the human body is fixed in a very narrow range between 7.35 and 7.45. A patient with an acidotic blood pH of 7.3 may be treated with an alkali such as sodium hydrogen carbonate. Why would this treatment raise the pH of the blood?
The Correct Answer and Explanation is:
A patient with an acidotic blood pH of 7.3 is experiencing a slight drop below the normal physiological range, which could impair cellular function and enzyme activity. Administering sodium hydrogen carbonate (NaHCO₃), commonly known as baking soda, helps correct this imbalance by acting as a buffer.
Sodium hydrogen carbonate is a weak base. When it dissolves in blood, it dissociates into sodium ions (Na⁺) and bicarbonate ions (HCO₃⁻). The bicarbonate ions play a central role in the body’s buffer system. They react with excess hydrogen ions (H⁺), which are responsible for the acidic condition. The chemical reaction is as follows:
H⁺ + HCO₃⁻ → H₂CO₃ → CO₂ + H₂O
Here, hydrogen ions combine with bicarbonate to form carbonic acid (H₂CO₃), which spontaneously breaks down into carbon dioxide and water. The carbon dioxide is exhaled by the lungs, effectively removing acid from the body. As a result, the concentration of hydrogen ions in the blood decreases, causing the pH to rise toward normal.
This treatment works efficiently because the body’s natural buffer system includes the bicarbonate buffer. Adding more bicarbonate enhances the blood’s capacity to neutralize acids without dramatically altering pH. It is a gentle correction that helps stabilize blood chemistry without triggering an alkaline overshoot.
Maintaining pH within its narrow window is critical. Even small deviations can affect oxygen transport, nerve function, and metabolic pathways. Sodium hydrogen carbonate helps prevent further acid buildup and allows physiological processes to continue unhindered. By restoring the acid–base balance, the patient’s health can be stabilized and improved, especially in conditions such as metabolic acidosis, where acid accumulates or bicarbonate is lost.
