what makes a good buffer? is it that it has a strong base and a strong acid?
and why is blood a good buffer? is that because the oxygen it carries acts as a strong base?
No, no, and no.
A buffer is made with a weak acid and its salt OR a weak base and its salt. For example, an acid buffer can be made with acetic acid and sodium acetate. A basic buffer can be made with NH3 and NH4Cl.
Blook is a good buffer because of the CO2.
H2O + CO2 ==> H^+ + HCO3^-
A good buffer is a solution that can resist changes in pH when small amounts of acid or base are added. Generally, a buffer consists of a weak acid and its conjugate base (or a weak base and its conjugate acid).
To determine if a buffer is good, you need to consider a few factors:
1. Effective range: A good buffer should have its buffering capacity within a pH range that is relevant to the system you are studying. For example, in biological systems, a pH range between 6 and 8 is common.
2. Concentration: A buffer should have sufficient concentrations of both the weak acid and its conjugate base (or weak base and its conjugate acid) to effectively resist changes in pH. Higher concentrations of buffer components generally result in better buffering capacity.
Regarding your second question, blood acts as a good buffer mainly due to the presence of carbonic acid-bicarbonate buffer system. Carbonic acid (H2CO3) is a weak acid, and bicarbonate ion (HCO3-) acts as its conjugate base. When an acid is added to blood, it reacts with bicarbonate ions to form carbonic acid. Similarly, when a base is added, it reacts with carbonic acid, converting it into bicarbonate ions.
However, the oxygen carried by blood does not act as a strong base. The primary role of oxygen in blood is to bind with hemoglobin for transport. Though oxygen can influence the pH indirectly, it does not function as a buffer component itself.
In summary, blood is a good buffer due to the carbonic acid-bicarbonate buffer system, which helps maintain the blood pH within a relatively narrow range despite metabolic acidosis or alkalosis.