We are familiar with the concept of pH, experienced middle school, and entered the health care mode in advance. In addition to the pH of the solution, the human body also has pH, which is judged according to the pH of the body fluid. PH 7 is neutral, 7 is alkaline, and the normal pH of human tissues should be 7-7.4. PH value, also known as pH value, hydrogen ion concentration index and pH value, is a measure of hydrogen ion activity in solution and also a measure of pH value of solution in general. There is no doubt that "H" in "pH" stands for hydrogen ion (H+), but the source of P is controversial. The first P stands for German "Potenz", which means strength and intensity. The first P stands for French puissance, which also means "strength and intensity". The second one is called "pondus hydrogenii" whose pH is Latin, that is, "the amount of hydrogen", and the first one is called potential hydrogen ii (the capacity of hydrogen) in Latin, which corresponds to potential hydrogen in English. The third view is that P is just a symbol chosen randomly by the proposer Sorensen, because he also used Q. In today's chemical world, P is added to dimensionless quantity to represent the negative logarithm of quantity, so P should be lowercase. Where do you know the concept of pH?