How Buffers Work

When weak acid (HA) and its conjugate base (A-) are mixed, both acid and base components remain in solution. This is because it does not react so much as the concentration changes. Acids and conjugate bases can react with each other, HA + A - → A - + HA, but if they exchange, they are only exchange sites and concentrations [HA] and [A -] do not change. In addition, HA and A - hardly react with water. By definition, weak acids are acids that rarely dissociate in water (ie, acids rarely lose their protons H + in water). Likewise, since the conjugate base A - is a weak base, it is rare to steal protons H + from water.

Therefore, weak acids and weak bases hardly react with water, so they remain in highly concentrated solutions. However, it may react with additional strong bases or strong acids.

When a strong base is added to the buffer, the weak acid abandons its H + and converts the base (OH -) to water (H 2 O) and conjugate base: HA + OH - → A - + H 2 O . As the added OH - is consumed by this reaction, the pH will only change slightly.

When a strong acid is added to the buffer, the weak base reacts with H + from the strong acid to form a weak acid HA: H + + A - → HA. Since H + is absorbed by A - instead of reacting with water to form H 3 O + (H +), the change in pH is slight.

Blood is a good example of how buffer solution works. The pH of the blood is about 4, and if it changes by only 0.2, it is sufficient to kill a human. This is the reason why your blood has a buffer, as the buffer prevents changes in the pH of the blood, and without them we will not survive. Blood contains three different buffer systems so that any acid / base entering it can be buffered. Bicarbonate buffer is one of them, it is a very important buffer. When blood system adds too much alkali, this is how bicarbonate buffer works:

Bicarbonate buffer is very important in the human body. They buffer very well the acids and bases in their bodies, so they work very well. This can be done because the bicarbonate buffer is in the form of carbonic acid and it is able to neutralize the matrix material placed in the blood of the human body by creating a neutral balance. The bicarbonate buffer may also be in the form of a conjugate base of carbonic acid and in this state they neutralize any acid placed in the human bloodstream by forming a neutral equilibrium system with the acid can do. These equalization systems are shown on the next page.

The bicarbonate-carbonate buffer acts like a phosphate buffer. Bicarbonate, similar to phosphate ion, is regulated by sodium in the blood. When sodium bicarbonate (NaHCO 3) is brought into contact with a strong acid such as HCl, carbonic acid (H 2 CO 3) (weak acid) NaCl is formed. When carbonic acid is brought into contact with a strong base such as NaOH, bicarbonate and water are formed. As with phosphate buffers, weak acids or weak bases capture free ions and prevent large pH changes. If the pH of the blood is within the normal range, bicarbonate ion and carbonic acid exist in the blood at a ratio of 20: 1. Bicarbonate is 20 times more potent than carbonic acid, and this capture system is most effective at buffering changes that make blood more acidic. This is convenient because most of the body's metabolic waste such as lactic acid and ketone are sour.