Chapter 7, Problem 129AE

Hemoglobin (abbreviated Hb) is a protein that is responsible for the transport of oxygen in the blood of mammals. Each hemoglobin molecule contains four iron atoms that are the binding sites for ${\text{O}}_{\text{2}}$ molecules. The oxygen binding is pH-dependent. The relevant equilibrium reaction is
${\text{HbH}}_{\text{4}}{}^{\text{4+}}\text{(}aq{\text{)+4O}}_{\text{2}}\text{(}g\text{)}\rightleftharpoons {\text{Hb(O}}_{\text{2}}{\text{)}}_{\text{4}}\text{(}aq{\text{)+4H}}^{\text{+}}\text{(}aq\text{)}$

Use Le Châtelier’s principle to answer the following.

a. What form of hemoglobin, ${\text{HbH}}_{\text{4}}{}^{\text{4+}}$ or ${\text{Hb(O}}_{\text{2}}{\text{)}}_{\text{4}}$ , is favored in the lungs? What form is favored in thecells?
b. When a person hyperventilates, the concentration of ${\text{CO}}_{\text{2}}$ in the blood is decreased. How does this affectthe oxygen-binding equilibrium? How does breathing into a paper bag help to counteract this effect?(See Exercise 130.)
c. When a person has suffered a cardiac arrest, injection of a sodium bicarbonate solution is given. Whyis this necessary? (Hint: ${\text{CO}}_{\text{2}}$ blood levels increase during cardiac arrest.)