11/13/2022 0 Comments Activity 3.4 linear dimensions![]() ![]() ![]() ![]() This was the original definition of Sørensen in 1909, which was superseded in favor of pH in 1924. The pH scale is logarithmic and therefore pH is a dimensionless quantity. Commercial standard buffer solutions usually come with information on the value at 25 ☌ and a correction factor to be applied for other temperatures. When more than two buffer solutions are used the electrode is calibrated by fitting observed pH values to a straight line with respect to standard buffer values. Further details, are given in the IUPAC recommendations. The reading from a second standard buffer solution is then adjusted, using the "slope" control, to be equal to the pH for that solution. To implement this approach to calibration, the electrode is first immersed in a standard solution and the reading on a pH meter is adjusted to be equal to the standard buffer's value. Two or more buffer solutions are used in order to accommodate the fact that the "slope" may differ slightly from ideal. IUPAC (International Union of Pure and Applied Chemistry) has proposed the use of a set of buffer solutions of known H + activity. It is calibrated against buffer solutions of known hydrogen ion activity. A combined glass electrode has an in-built reference electrode. To apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. pH = − log ( a H + ) = − log ( / M ), the "Nernstian slope". The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution. Acidic solutions (solutions with higher concentrations of H + ions) are measured to have lower pH values than basic or alkaline solutions. In chemistry, pH ( / p iː ˈ eɪ tʃ/), historically denoting "potential of hydrogen" (or "power of hydrogen"), is a scale used to specify the acidity or basicity of an aqueous solution. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |