The logarithmic way of expressing the concentration of hydrogen ions in simple whole numbers between 0 and 14 is called pH. The ‘p’ refers to the logarithmic scale in negative log and ‘H’, to the concentration of hydrogen ions in solution. The negative sign indicates that as the concentration of hydrogen ions will increase in solution, pH will go down towards 1. However, pH increases as the concentration of hydrogen ions decrease.
pH = -log [H+]
Why is pH important
The scale ranging from 1.00 to 14.00 providing us with the concentration of hydrogen ions is called the pH scale.
The pH is a very important parameter, reflecting the chemical condition and environment of a solution or chemical. It can control the biochemical cycles going inside organisms, microbial activity, availability of nutrients, the behavior of enzymes and other chemical species, and the optimum operating conditions for various chemical species.
Importance of pH maintenance
Most of the chemical reactions in chemistry being pH-sensitive make pH a very important parameter. For example
The biochemical catalysts i.e. enzymes are sensitive to changes in pH. The change of pH changes the shapes of active sites present on enzymes and in fact, the reaction action centre in enzymes, altering the way a particular enzyme acts and what it acts upon. For example, the complex formation of EDTA (Ethylenediaminetetraacetic acid) with calcium occurs at pH 12.
Human blood works at optimum efficiency at a pH range (7.35 to 7.45). A change in pH over this limit increases the chances of alkalosis or acidosis. Alkalosis is the condition of having alkaline blood (pH > 7.45), and acidosis arises from the acidity of blood (pH < 7.35).
Acid-base pigments use pH change to indicate the change in the environment of solutions. For example,
Phenolphthalein changes its color from transparent to violet-pink in basic environments (pH < 10.5). Phenolphthalein turns pink in an alkaline environment, whereas it changes to transparent when pH starts to decrease (pH > 8.3). When does phenolphthalein turn pink?
All acid-base indicators have this phenomenon inside which makes them able to show pH change even for shorter ranges. Other such indicators include methyl red, methyl orange, bromothymol blue, bromocresol green, phenol red, and thymol blue, etc.
Moreover, all pH-dependent reactions occurring depend on the pH maintenance somehow. It means that the pH maintenance is crucial and inevitable depending on the effects, a pH change will have on reaction progress.
This pH maintenance is provided mainly by the buffers.