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Having gone through middle school and adopted a health-conscious lifestyle at an early age, we are certainly familiar with the concept of pH. In addition to solutions having a pH level, the human body also has a pH level, which is determined by the acidity or alkalinity of bodily fluids. A pH value of 7 is neutral; values below 7 indicate acidity, while values above 7 indicate alkalinity. The normal pH range for human tissues is between 7 and 7.4. pH, also known as the pH value, hydrogen ion concentration index, or acidity level, is a scale that indicates the activity of hydrogen ions in a solution; it is essentially the measure of how acidic or basic a solution is. pH = -lg. “It is beyond doubt that the “H” in “pH” stands for hydrogen ion, H+. However, the origin of the “p” value is subject to debate and there is no consensus on it. The first one, denoted by p, represents the German word “Potenz,” which means strength or intensity; it is also said to represent the French word “puissance,” which likewise means strength or intensity ； The second term, pH, represents the Latin word “pondus hydrogenii”, which means “quantity of hydrogen”. Another theory is that it comes from the Latin word potentia hydrogenii, meaning “capacity of hydrogen”, corresponding to potential hydrogen in English. The third view is that p is merely a symbol arbitrarily chosen by the proponent Sorensen, since he also used q. In modern chemistry, the symbol p is placed in front of a dimensionless quantity to denote the negative logarithm of that quantity; therefore, p should be written in lowercase.