Human blood has a narrow Ph range of `7.3-7.4`, which must be maintained for methabolic processes to function properly. To keep the Ph in this range requires a delicate balance between the concentration of the conjugate acid-base pairs making upto the buffer system. The main buffer is a carbonic acid/ hydrogencarbonate system, which involves the following three equilibria.
`CO_(2)(g)hArrCO_(2)(aq)`
`CO_(2)(aq)+H_(2)O(l)hArrH_(2)CO_(3)(aq)`
`H_(2)CO(aq)+H_(2)O(l)hArrHCO_(3)^(-)(aq)+H_(3)O^(+)(aq)`
Carbonic acid `(H_(2)CO_(3))` is a weak acid and `HCO_(3)^(-)`(aq) is its conjugate base. At the temperature of the human body, the `pK_(a)` for carbonic acid is 6.4 However, the normal concentration of `CO_(2)(g)` in the lungs maintanis a ratio of `HCO_(3)^(-)(aq)//H_(2)CO_(3)(aq)` in blood plasma of about `8:1`.
The carbonic acid concentration in the bloos is largely controlled by breathing and respiration. Hydrogencarbonate ion concentration is largely controlled by excreation in urine.
If blood pH rises above `7.4`, a potentially life-threatening conditon called alkalosis can result. This can happen in patients who are hyperventilating from severse anxiety, or in climbers suffereing from oxygen deficency at high altitude. (Given: log 2=0.3)
Calculate pH of blood at the temperature of the human body.

Options

A. `7.4`
B. `7.3`
C. `7.35`
D. `6.7`

Answer

b