The concept of pKw is used in the field of chemistry . The notion refers to a measurement that is calculated by the negative logarithm ( -log ) of the dissociation or ionization constant of water .
It is important to keep in mind that pKw , pH , pKa , pKb and other scales and constants refer to the alkalinity or acidity of a solution and the strength of bases and acids. The appearance of a letter p at the beginning always reveals that it is a negative logarithm: in this case, pKw is the -log of Kw .
Now, what is Kw ? This is known as the ionization or dissociation constant of water , also called the ionic product of water .
Water can dissociate into its ions, although this dissociation is weak. The ionic product tends to remain constant, and Kw is the dissociation constant.
It can be said that Kw is the equilibrium constant linked to the molarity of water in an aqueous solution. It should be noted that molarity or molar concentration indicates, in a solution, what the concentration of a solute is: it is a volume that depends on the temperature .
Therefore, although the molarity is practically constant in aqueous solutions, the pKw changes with temperature . If the temperature increases, the pKw decreases; Conversely, when the temperature decreases, the pKw increases.
Due to this rule, the autoionization of water usually grows with temperature. On the other hand, it must be taken into account that pressure also affects -although slightly- the pKw .
In order to carry out the measurement of an aqueous medium, the term pOH is used, which is complemented by the term pH. Specifically, it is established that pH added to pOH is equal to pKw.
When calculating the pH, the formula to use is different depending on whether it is a strong acid, a medium-strength acid, anthophers, salts, weak bases or strong bases, for example. Thus, in the case of a weak base the pH will be obtained with this formula: 7 + pKa+ log (base) / 2.
In the same way, we cannot ignore that Pkw is also the name of a company from Madrid. We are referring to Pkw Logistik Iberia, which has its headquarters in an industrial estate in the town of Valdemoro (Madrid) and which specializes in the national and international logistics and transport sector.
Likewise, PKW is the name of a German company specialized in automobiles, which has a wide variety of cars for sale, among which some of the reference brands such as BMW stand out.
Not to mention that PKW OEM is the name of a spare parts store located in Santiago de Chile.
In addition, we have to establish that PKW is the name of an antenna system that is vertical and that offers permanent coverage.