Brief introduction of pH value pH value, also known as hydrogen ion concentration index and pH value, is a measure of hydrogen ion activity in solution and also a measure of acid-base degree of solution in general sense. This concept is 1909 by Danish biochemist s? Peter Laurits's? Renson proposed. P stands for German Potenz, strength or concentration, and H stands for hydrogen ion (H). Sometimes pH is also written in Latin as pondus hydrogenii. Under normal conditions (about 25℃ and 298K), when pH; 7, the solution is alkaline, pH=7, the solution is neutral. Note: The pH value is allowed to be less than 0, for example, the pH value of hydrochloric acid (10 mol/L) is-1. Edit this paragraph and define the calculation formula of ph value as follows: where [H] refers to the activity of hydrogen ions in solution (sometimes written as [H3O], the activity of hydronium ions), and the unit is mol/L. In dilute solution, an aqueous solution with pH=7 (such as pure water) is neutral at standard temperature and pressure, because at standard temperature and pressure, The product of the concentrations of hydrogen ions and hydroxyl ions naturally ionized in water (ion product constant of water) is always/kloc-0 /×10-654338. PH less than 7 means that the concentration of H is greater than that of OH, so the solution is acidic, while pH greater than 7 means that the concentration of H is less than that of OH, so the solution is alkaline. Therefore, the smaller the pH value, the stronger the acidity of the solution. The greater the pH value, the stronger the alkalinity of the solution. Under the condition of non-aqueous solution or non-standard temperature and pressure, pH=7 does not necessarily mean that the solution is neutral, which needs to be determined by calculating the ionization constant of the solvent under this condition. For example, at the temperature of 373K( 100℃), pH=6 is a neutral solution. The clinical significance of editing pH in this section. Normal situation: 7.11~ 7.365 ~10, 7.09 ~ 7.3030, 7.2 1 ~ 7.38 > 1 hour 7.26 ~ 7.49 1 day 7.29 ~ 7.45 and then 7.35 ~ 7.45(H+ concentration 36 ~ 44 nmol/L) increased: metabolic alkali decreased: metabolic acidosis: ketone. Respiratory acidosis: pulmonary heart disease, respiratory failure, pulmonary edema, etc. Edit the measurement method of pH value in this paragraph. BPH-200A Chinese online PH meter is a brand-new ph analyzer of our company. The instrument is a highly intelligent on-line continuous monitor, which consists of two parts: sensor and secondary instrument. Can be equipped with three or two composite electrodes to meet various use occasions. Equipped with pure water and ultrapure water electrodes, it can be used to measure the pH value of water with conductivity less than 3μs/cm (such as chemical makeup water, saturated steam, condensed water, etc.). ). There are many methods to measure the pH value of solution: adding a pH indicator to the solution to be measured, different indicators will change color according to different pH values, and the range of pH value can be determined according to the study of the indicator. When titrating, an accurate pH standard can be made. Use pH test paper, including universal test paper and precision test paper. Dip a little solution to be tested on the test paper with a glass rod, and then compare it with the colorimetric chart according to the color change of the test paper to get the pH value of the solution. The above table is equivalent to a color chart. The pH test paper cannot show the pH value of the oil, because the pH test paper is made of iron hydroxide, which is used to measure the pH value of the solution to be tested, but the oil does not contain iron, so the pH test paper cannot show the pH value of the oil. Use a pH meter, which is an instrument for measuring the pH value of a solution. It measures the pH value of the solution through a pH selective electrode (such as a glass electrode). The acidity meter can be accurate to two decimal places.