InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
The pH of blood circulating in a human body is maintained around. `7.4` by the action of the buffer systemA. `CH_(3)COOH//CH_(3)COONa`B. `NH_(4)CI//NH_(3)`C. `H_(2)PO_(4)^(-)//HPO_(4)^(2-)`D. `CO_(2)//HCO_(3)^(-)` |
|
Answer» Correct Answer - D Blood, as a buffer solution, contains `H_(2)CO_(3)` as well as other conjugate acid-base pairs. Carbon dioxide might not appear to be an acid, since it has no proton of it froms carbonic acid `(H_(2)CO_(3))`: `CO_(2)(aq.)+H_(2)hArrH_(2)CO_(3)(aq.)` The conjugate base of carbonic acid is the bicarbonate ion, `HCO_(3)^(-)`: `H_(2)CO_(3)(aq.)hArrHCO_(3)^(-)(aq.)+H^(+)(aq.)` The overall reaction relating carbon dioxide and bicarbonate ion is the sum of these two reactions: `CO_(2)(aq.)+H_(2)OhArrHCO_(3)^(-)(aq.)+H^(+)(aq.)` The `pK_(a)` of the equilibrium for this buffer system is `6.37`. A second class of physiological buffer is based on the dihydrogen phosphate anion `(H_(2)PO_(4)^(-))` which is a weak acid and hydrogen phosphate `(HPO_(4)^(2-))`, its conjugate base: `H_(2)PO_(4)^(-)(aq.)hArrHPO_(4)^(2-)(aq.)+H^(+)(aq.)` Again the `pK_(a)(7.21)` is close to the physiological pH. |
|