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pH and its Importance

The pH (hydrogen ion potential) of a solution is defined as

pH = - log10 (H+) , where (H+) is the hydrogen ion concentration. pH

scale (from potential of Hydrogen) is the logarithm of the reciprocal of

hydrogen- ion concentration in gram atoms per litre and provides a

measure on a scale from 0 to 14 of the acidity or alkalinity of a solution

(where 7 is neutral and greater than 7 is more basic and less than 7 is

more acidic). When pH goes off microbes in the blood can change

shape, mutate, become pathogenic, constructive enzymes turn

destructive, oxygen delivery to cells suffer, mineral assimilation can get

thrown off and organs of your body can become compromised, like your

heart or brain. The pH balance of the human bloodstream is recognizedby all medical physiology texts as one of the most important biochemical

balances in all of human body chemistry. All biochemical reactions and

electrical (life) energy are under pH control. The higher (more alkaline)

the pH of a substance or solution, the more electrical resistance that

substance or solution holds. Therefore, electricity travels slower with

higher pH.

Ideally, the pH of the blood should be

maintained at 7.4. If the pH drops below 6.8 or rises above 7.8, death

may occur. Buffers in the blood to protect against large changes in

pH. If, for instance, the pH of the blood and external fluid is too

low (too many H+ ions), then an excess of H+ ions will enter the cell.

In order to maintain the proper chemical composition inside the

cells, the chemical composition of the fluids outside the cells must be

kept relatively constant (homeostasis). The most important way that

the pH of the blood is kept relatively constant is by buffers dissolved

in the blood. By far the most important buffer for maintaining acid-

base balance in the blood is the carbonic-acid-bicarbonate buffer. It

is the kidneys that ultimately remove (from the body) H+ ions andother components of the pH buffers that build up in excess. The

increased-breathing response to exercise helps to counteract the pH-

lowering effects of exercise by removing CO2, a component of the

principal pH buffer in the blood.

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pH Measurement Conventional methods :

Conventional techniques of pH measurement include

measurement using pH strips and pH electrodes. With pH strips, pH

is measured as a change in the colour of the strip. However, pH strips

suffer from poor resolution and poor sensitivity. Again, real time

measurement is not possible with pH strips. pH electrodes uses

Ag/AgCl electrodes, offer better resolution and are more reliable.

However, pH electrodes are made of glass and are fragile. They have

a comparatievely larger size and suffer from less sensitivity .

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Substance pH A ComparisionMATERIAL pH Value

Lemon juice 2.4

Cola 2.5

Vinegar 2.9

Orange 3.5

Beer 4.5

Acid Rain