Question

please explain why the pH value of blood changes minimally when hydrochloric acid and sodium hydroxide is added

Answer 1

Maintaining a constant blood pH is critical for the proper functioning of our body,The buffer that maintains the pH of human blood involves a carbonic acid-bicarbonate ion system.

When any acidic substance (like hydrochloric acid) enters the bloodstream, the bicarbonate ions neutralize the hydronium ions forming carbonic acid and water. Carbonic acid is already a component of the buffering system of blood. Thus hydronium ions are removed, preventing the pH of blood from becoming acidic.

On the other hand, when a basic substance(like sodium hydroxide) enters the bloodstream, carbonic acid reacts with the hydroxide ions producing bicarbonate ions and water. Bicarbonate ions are already a component of the buffer. In this manner, the hydroxide ions are removed from blood, preventing the pH of blood from becoming basic.

In the process of neutralizing hydronium ions or hydroxide ions, the relative concentrations of carbonic acid and bicarbonate ions fluctuate in the blood stream.
But this slight change in the concentrations of the two components of the buffering system doesn’t have any adverse effect; the critical thing is that this buffering mechanism prevents the blood from becoming acidic or basic.