Precautions for using glass electrode of pH meter
(1) The accuracy of the measurement results first depends on the accuracy of the PH standard value of the standard buffer solution. Therefore, the buffer solution should be prepared and stored according to GB11076-89 "Preparation Method of Buffer Solution for pH Measurement".
(2) Glass electrodes and Gangong electrodes should be selected, processed and installed according to specifications.
(3) The pH value of water samples should be measured on site. Otherwise, the samples should be kept at 0-4°C after sampling and measured within 6 hours after sampling. Pure water is neutral, with a pH value of 7.0 at 25 degrees. Solutions below this value are acidic, and solutions above this value are alkaline. Pure water also ionizes (a decomposition process that breaks down charged ions) to produce hydrogen ions
H+ and hydroxyl ions OH- (+ and - are superscripts, indicating positive and negative electricity). It has been proven that at 25 degrees, the hydrogen ions and hydroxide ions in the aqueous solution (whether it contains acid or alkali) The product of the concentrations is a constant, which is always equal to 10 to the power of -14. For example, when the hydrogen ion concentration is 0.1 mol/L, the hydroxide ion concentration must be 10 to the power of -13 mol/L. The ionization process of water can be expressed as follows: H2O == (H+) + (OH-). This is not a mathematical equation. It only represents a process, that is, a water molecule can decompose into a hydrogen ion and a hydroxide ion. . Since the degree of decomposition of water is affected by temperature, the pH value in pure water (without any impurities) is not always 7.0. Generally speaking, acidity means that there are more hydrogen ions than hydroxyl ions in the solution. Generally speaking, the pH value will not be less than 0 or greater than 14. The concentration of hydrogen ions or hydroxide ions in such a solution will be very large (more than 1 mol/L), and the acidity or alkalinity of the solution will It is expressed directly in terms of concentration, not pH value.
