The pH tells you if a patient is acidotic or alkalotic. The relationship with Hydrogen ions (H+) is what determines a molecule’s acidic or basic (alkalotic) profile. A molecule which freely gives away H+ ions is called an acid (for example, Carbonic acid). A solution with lots of acids contains a lot of free Hydrogen ions. In contrast, a molecule which freely receives H+ ions is called an alkali, or base. A solution with lots of alkali contains very few Hydrogen ions. Confusingly, pH is an inverse of hydrogen ion concentration; the more hydrogen ions present, the lower the pH. The normal range for the pH is tightly controlled between 7.35 and 7.45.