What gradient does a pH meter?
The slope of a pH meter is used to convert the millivolt signal of an electrode into a pH value. It refers to the difference in voltage measured with different buffer solutions divided by the difference in buffer solution pl value. The slope in a pH meter is calculated based on the Nernst equation, and usually only appears after calibration. The slope is an important indicator for determining whether the electrode life has been exhausted. There are generally three levels of electrode lifespan. After calibration, the slope of a new electrode is between 95% and 105%. If the slope is lower than 90%, it is recommended to replace the electrode, otherwise it will affect its measurement accuracy. PH calibration solution for pH meter calibration. The calculation of slope is related to the electrode measurement of the potential of the solution you have prepared. Three standard buffer solutions are usually selected for calibration, and if all three are involved in calibration, the slope will correspondingly differ.
A pH meter refers to an instrument used to determine the acidity or alkalinity of a solution. A pH meter operates based on the principle of a primary battery. The electromotive force between the two electrodes of the primary battery is determined by Nernst's law, which is related to both the electrode properties and the concentration of hydrogen ions in the solution. There is a corresponding relationship between the electromotive force of the primary battery and the concentration of hydrogen ions, and the negative logarithm of the concentration of hydrogen ions is the pH value. A pH meter is a common analytical instrument widely used in fields such as agriculture, environmental protection, and industry. Soil pH value is one of the important basic properties of soil. During the pH measurement process, factors such as the temperature and ionic strength of the solution to be tested should be considered
What is pH? PH is an abbreviation for the Latin word "Pondus hydrogeni" (Pondus=pressure, pressure hydrogenum=hydrogen), used to measure the activity of hydrogen ions in a substance. This activity is directly related to the acidity, neutrality, and alkalinity of aqueous solutions. Water is chemically neutral, but it is not without ions, and even chemically pure water has trace amounts of dissociation: strictly speaking, hydrogen nuclei do not exist in a free state before hydration with water molecules.
H2O+ H2O=H3O++ OHˉ, Due to the fact that the concentration of hydrated hydrogen ions (H3O+) is equivalent to that of hydrogen ions (H+), the above equation can be simplified into the following commonly used form: H2O=H++OH ˉ, where the positive hydrogen ion is represented as "H+ion" or "hydrogen nucleus" in chemistry. Hydrated hydrogen nuclei are represented as "hydrated hydrogen ions". Negative hydroxide ions are called "hydroxide ions". Using the law of mass action, an equilibrium constant can be found to represent the dissociation of pure water: K=H3O+× OH - -- H2O. Since only a very small amount of water is dissociated, the mass molar concentration of water is actually a constant, and the equilibrium constant K can be used to calculate the ion product KW of water. KW=K × H2O KW=H3O+· OH -=10-7 · 10-7=10-14mol/l (25 ℃), which means that for one liter of pure water, there are 10-7 moles of H3O+ions and 10-7 moles of OH - ions at 25 ℃. In neutral solution, the concentration of hydrogen ions H+and hydroxide ions OH - is both 10-7mol/l.
