Q. 10.80 - An Introduction to General, Organic, and Biological Chemistry

Question

In the blood plasma. pH is maintained by the carbonic acid bicarbonate buffer system, $(10,8)$

a. How is pH maintained when acid is added to the buffer system?

b. How is pH maintained when base is added to the buffer system?

Step-by-Step Solution

Answer

(Part a)As a result, the${\mathrm{H}}_3{\mathrm{O}}^{+}$ ion concentration of the solution does not change practically, and the solution remains constant

(Part b)As a result, the${\mathrm{OH}}^{-}$ ion concentration of the solution does not change significantly, and the pH of the solution remains constant

Step 1:Introduction (Part a)

A base is a molecule or ion that can accept a hydrogen ion from an acid. Acidic substances are typically identified by their sour taste. An acid is a molecule that can donate an H+ ion while also remaining energetically favorable after losing an H+ ion.

Step 2:acid is added to the buffer system (part a)

(a) When acid is added to buffer system, the ${\mathrm{H}}_3{\mathrm{O}}^{+}$ion given by acid combine with the ${\mathrm{HCO}}_3^{-}$ion to create a weakly molecule that it became ionized${\mathrm{H}}_2{\mathrm{CO}}_3$.

${\mathrm{HCO}}_3^{-}+{\mathrm{H}}_3{\mathrm{O}}^{+}\to {\mathrm{H}}_2{\mathrm{CO}}_3+{\mathrm{H}}_2\mathrm{O}$

As a result, the${\mathrm{H}}_3{\mathrm{O}}^{+}$ ion concentration of the solution does not change practically, and the solution remains constant

Step 3:Introduction (Part b)

A buffer is an aqueous solution made up of a weak acid and its salt (acid buffer) or a weak base and its base buffer (salt) (basic buffer).Its pH changes very little when a small amount of strong acid or base is added to it, and it is thus used to keep the pH of a solution from changing.

Step 4:When base is added to buffer system (part b)

(b) When the base is added to the buffer system, its ion combines with the ${\mathrm{H}}_3{\mathrm{O}}^{+}$ion already present to form weakly ionized molecules of ${\mathrm{H}}_2\mathrm{O}$

${\mathrm{H}}_3{\mathrm{O}}^{+}+{\mathrm{OH}}^{-}\to {\mathrm{H}}_2\mathrm{O}$

As a result, the${\mathrm{OH}}^{-}$The solution's ion concentration does not change significantly.  and the pH of The solution does not modify .