How Do We Measure Acidity or Alkalinity?

Acidity and alkalinity indicates the level of hydrogen ions in a waterbased fluid and we use the pH scale to assess a fluid. The pH scale ranges from 0 to 14, with 0 being the most acidic and 14 being the most basic as
shown in Figure 1.9. Thus, a pH of 7 is said to be neutral because it splits the two extremes. A pH lower that 7 means a higher hydrogen ion concentration and thus greater acidity. On the other hand, an alkaline solution
has a pH greater than 7 and has a lower level of hydrogen ions. The pH scale was conceived by Sören Sörensen who was a pretty good biochemist and an excellent brewer of beer! Back in the days before sophisticated pH meters, one could speculate as to whether a fluid was acidic or basic based on taste. Acidic substances tend to have a sour taste (lemon juice, orange juice), while more alkaline substances taste bitter. So what is the big deal about pH? Our body has but a narrow pH range

at which it can function appropriately. As noted on the scale in Figure 1.9, the pH of our blood is about 7.4. This means that the pH of our body is slightly basic. If the pH falls below or above 7.4 these conditions are referred to as acidosis and alkalosis, respectively. Nearly all chemical reactions in our body are controlled by enzymes, most of which function in our best interest at a pH around 7.4. Thus, when our pH falls or climbs, the efficiency of many enzymes is significantly affected. Some enzymes will work harder and others will work less hard, thus impacting key chemical reactions in our body. This can compromise normal function and possibly our vitality.
 

Inherent to our body are systems that help us maintain the pH of our body fluid (for example, blood) around 7.4. These systems are called buffering systems and they act either to soak up excessive hydrogen ions or to release them when our body pH begins to change. Thus pH can be maintained at the 7.4 ideal despite changing internal factors.